Wireless power receiving device, wireless power transmitting device, and method for calibrating power using the same

ABSTRACT

A wireless power transmitter according to one embodiment of the present disclosure transmits wireless power to a wireless power receiver, receives a first received power packet including an estimated received power value indicating a first calibration data point from the wireless power receiver after a negotiation phase, transmits ACK in response to the first received power packet, receives a second received power packet including an estimated received power value indicating a second calibration data point from the wireless power receiver, transmits ACK in response to the second received power packet, receives a new second received power packet including an estimated received power value indicating a third calibration data point from the wireless power receiver, transmits ACK in response to the new second received power packet, and constructs a power calibration curve using the first received power packet, the second received power packet, and the new second received power packet.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.17/185,306, filed on Feb. 25, 2021, which is a continuation ofInternational Application No. PCT/KR2020/013484, filed on Oct. 5, 2020,which claims the benefit of earlier filing date and right of priority toKorean Patent Application No. 10-2019-0122594, filed on Oct. 2, 2019,the contents of which are all hereby incorporated by reference hereintheir entirety.

BACKGROUND OF THE DISCLOSURE Field of the Disclosure

The present disclosure relates to a wireless power transmitting device,a wireless power receiving device receiving wireless power from thewireless power transmitting device, and a method for calibrating power.

Related Art

The wireless power transfer (or transmission) technology corresponds toa technology that may wirelessly transfer (or transmit) power between apower source and an electronic device. For example, by allowing thebattery of a wireless device, such as a smartphone or a tablet PC, andso on, to be recharged by simply loading the wireless device on awireless charging pad, the wireless power transfer technique may providemore outstanding mobility, convenience, and safety as compared to theconventional wired charging environment, which uses a wired chargingconnector. Apart from the wireless charging of wireless devices, thewireless power transfer technique is raising attention as a replacementfor the conventional wired power transfer environment in diverse fields,such as electric vehicles, Bluetooth earphones, 3D glasses, diversewearable devices, household (or home) electric appliances, furniture,underground facilities, buildings, medical equipment, robots, leisure,and so on.

The wireless power transfer (or transmission) method is also referred toas a contactless power transfer method, or a no point of contact powertransfer method, or a wireless charging method. A wireless powertransfer system may be configured of a wireless power transmittersupplying electric energy by using a wireless power transfer method, anda wireless power receiver receiving the electric energy being suppliedby the wireless power transmitter and supplying the receiving electricenergy to a receiver, such as a battery cell, and so on.

The wireless power transfer technique includes diverse methods, such asa method of transferring power by using magnetic coupling, a method oftransferring power by using radio frequency (RF), a method oftransferring power by using microwaves, and a method of transferringpower by using ultrasound (or ultrasonic waves). The method that isbased on magnetic coupling is categorized as a magnetic induction methodand a magnetic resonance method. The magnetic induction methodcorresponds to a method transmitting power by using electric currentsthat are induced to the coil of the receiver by a magnetic field, whichis generated from a coil battery cell of the transmitter, in accordancewith an electromagnetic coupling between a transmitting coil and areceiving coil. The magnetic resonance method is similar to the magneticinduction method in that is uses a magnetic field. However, the magneticresonance method is different from the magnetic induction method in thatenergy is transmitted due to a concentration of magnetic fields on botha transmitting end and a receiving end, which is caused by the generatedresonance.

SUMMARY

A technical object of the present disclosure is to provide a wirelesspower transmitting device capable of detecting a foreign object moreaccurately between the wireless power transmitting device and a wirelesspower receiving device, the wireless power receiving device, and amethod for calibrating power using the devices.

Technical objects to be achieved by the present disclosure are notlimited to the aforementioned technical objects, and other technicalobjects not described above may be evidently understood by a personhaving ordinary skill in the art to which the present disclosurepertains from the following description.

To solve the problem above, a wireless power transmitting deviceaccording to one embodiment of the present disclosure is a wirelesspower transmitting device transmitting wireless power to a wirelesspower receiving device; and receives a first received power packetincluding an estimated received power value fora first calibration datapoint from the wireless power receiving device after a negotiationphase, transmits ACK in response to the first received power packet,receives a second received power packet including an estimated receivedpower value fora second calibration data point from the wireless powerreceiving device, transmits ACK in response to the second received powerpacket, receives a new second received power packet including anestimated received power value fora third calibration data point fromthe wireless power receiving device, transmits ACK in response to thenew second received power packet, and constructs a power calibrationcurve based on the first received power packet, the second receivedpower packet, and the new second received power packet.

To solve the problem above, a wireless power receiving device accordingto one embodiment of the present disclosure is a wireless powerreceiving device receiving wireless power from a wireless powertransmitting device; and transmits a first received power packetincluding an estimated received power value fora first calibration datapoint to the wireless power transmitting device after a negotiationphase, receives ACK in response to the first received power packet fromthe wireless power transmitting device, transmits a second receivedpower packet including an estimated received power value fora secondcalibration data point to the wireless power transmitting device,receives ACK in response to the second received power packet from thewireless power transmitting device, transmits a new second receivedpower packet including an estimated received power value fora thirdcalibration data point to the wireless power transmitting device, andreceives ACK in response to the new second received power packet fromthe wireless power transmitting device.

To solve the problem above, a wireless power receiving device accordingto one embodiment of the present disclosure is a wireless powerreceiving device receiving wireless power from a wireless powertransmitting device; and transmits a first received power packetincluding an estimated received power value fora first calibration datapoint to the wireless power transmitting device after a negotiationphase, receives ACK in response to the first received power packet fromthe wireless power transmitting device, transmits a second receivedpower packet including an estimated received power value fora secondcalibration data point to the wireless power transmitting device,receives ACK in response to the second received power packet from thewireless power transmitting device, and based on change of a targetoperating point, transmits a new second received power packet includingan estimated received power value fora third calibration data point tothe wireless power transmitting device or transmits a new first receivedpower packet including an estimated received power value fora new firstcalibration data point and a new second received power packet includingan estimated received power value indicating a new second calibrateddata point to the wireless power transmitting device.

Other specific matters of the present disclosure are included in thedetailed description and drawings.

Advantageous Effects

According to the present disclosure, a foreign object between a wirelesspower transmitting device and a wireless power receiving device may bedetected more accurately.

The effects according to the present disclosure is not limited by thecontents exemplified above, and more various effects are included in thepresent disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a wireless power system (10) according toan exemplary embodiment of the present disclosure.

FIG. 2 is a block diagram of a wireless power system (10) according toanother exemplary embodiment of the present disclosure.

FIG. 3 a shows an exemplary embodiment of diverse electronic devicesadopting a wireless power transfer system.

FIG. 3 b shows an example of a WPC NDEF in a wireless power transfersystem.

FIG. 4 is a block diagram of a wireless power transfer system accordingto another exemplary embodiment of the present disclosure.

FIG. 5 is a state transition diagram for describing a wireless powertransfer procedure.

FIG. 6 shows a power control method according to an exemplary embodimentof the present disclosure.

FIG. 7 is a block diagram of a wireless power transmitter according toanother exemplary embodiment of the present disclosure.

FIG. 8 is a block diagram of a wireless power receiver according toanother exemplary embodiment of the present disclosure.

FIG. 9 shows operation statuses of a wireless power transmitter and awireless power receiver in a shared mode according to an exemplaryembodiment of the present disclosure.

FIG. 10 is a state diagram illustrating a two-point power calibrationmethod.

FIG. 11 is a graph illustrating a power calibration curve according to atwo-point power calibration method.

FIG. 12 is a flow diagram illustrating a multi-point power calibrationmethod according to one embodiment.

FIG. 13 illustrates a format of a received power packet according to oneembodiment.

FIG. 14 is a state diagram illustrating a multi-point power calibrationmethod using a plurality of RP/2s according to one embodiment.

FIG. 15 is a graph illustrating a power calibration curve according to amulti-point power calibration method using a plurality of RP/2saccording to one embodiment.

FIG. 16 is a graph illustrating a power calibration curve according to amulti-point power calibration method using a plurality of RP/2saccording to another embodiment.

FIG. 17 is a state diagram illustrating a multi-point power calibrationmethod using RP/3 according to one embodiment.

FIG. 18 is a graph illustrating a power calibration curve according to amulti-point power calibration method using RP/3 according to oneembodiment.

FIG. 19 is a flow diagram illustrating a power re-calibration methodaccording to one embodiment.

FIG. 20 is a state diagram illustrating a power re-calibration methodaccording to one embodiment.

FIG. 21 is a graph illustrating a power calibration curve according to apower re-calibration method according to one embodiment.

FIG. 22 is a flow diagram illustrating a power calibration methodaccording to one embodiment.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

In this specification, “A or B” may refer to “only A”, “only B” or “bothA and B”. In other words, “A or B” in this specification may beinterpreted as “A and/or B”. For example, in this specification, “A, B,or C” may refer to “only A”, “only B”, “only C”, or any combination of“A, B and C”.

The slash (/) or comma used in this specification may refer to “and/or”.For example, “A/B” may refer to “A and/or B”. Accordingly, “A/B” mayrefer to “only A”, “only B”, or “both A and B”. For example, “A, B, C”may refer to “A, B, or C”.

In this specification, “at least one of A and B” may refer to “only A”,“only B”, or “both A and B”. In addition, in this specification, theexpression of “at least one of A or B” or “at least one of A and/or B”may be interpreted to be the same as “at least one of A and B”.

Also, in this specification, “at least one of A, B and C” may refer to“only A”, “only B”, “only C”, or “any combination of A, B and C”. Also,“at least one of A, B or C” or “at least one of A, B and/or C” may referto “at least one of A, B and C”.

In addition, parentheses used in the present specification may refer to“for example”. Specifically, when indicated as “control information(PDCCH)”, “PDCCH” may be proposed as an example of “controlinformation”. In other words, “control information” in thisspecification is not limited to “PDCCH”, and “PDDCH” may be proposed asan example of “control information”. In addition, even when indicated as“control information (i.e., PDCCH)”, “PDCCH” may be proposed as anexample of “control information”.

In the present specification, technical features that are individuallydescribed in one drawing may be individually or simultaneouslyimplemented. The term “wireless power”, which will hereinafter be usedin this specification, will be used to refer to an arbitrary form ofenergy that is related to an electric field, a magnetic field, and anelectromagnetic field, which is transferred (or transmitted) from awireless power transmitter to a wireless power receiver without usingany physical electromagnetic conductors. The wireless power may also bereferred to as a wireless power signal, and this may refer to anoscillating magnetic flux that is enclosed by a primary coil and asecondary coil. For example, power conversion for wirelessly chargingdevices including mobile phones, cordless phones, iPods, MP3 players,headsets, and so on, within the system will be described in thisspecification. Generally, the basic principle of the wireless powertransfer technique includes, for example, all of a method oftransferring power by using magnetic coupling, a method of transferringpower by using radio frequency (RF), a method of transferring power byusing microwaves, and a method of transferring power by using ultrasound(or ultrasonic waves).

FIG. 1 is a block diagram of a wireless power system (10) according toan exemplary embodiment of the present disclosure.

Referring to FIG. 1 , the wireless power system (10) include a wirelesspower transmitter (100) and a wireless power receiver (200).

The wireless power transmitter (100) is supplied with power from anexternal power source (S) and generates a magnetic field. The wirelesspower receiver (200) generates electric currents by using the generatedmagnetic field, thereby being capable of wirelessly receiving power.

Additionally, in the wireless power system (10), the wireless powertransmitter (100) and the wireless power receiver (200) may transceive(transmit and/or receive) diverse information that is required for thewireless power transfer. Herein, communication between the wirelesspower transmitter (100) and the wireless power receiver (200) may beperformed (or established) in accordance with any one of an in-bandcommunication, which uses a magnetic field that is used for the wirelesspower transfer (or transmission), and an out-band communication, whichuses a separate communication carrier. Out-band communication may alsobe referred to as out-of-band communication. Hereinafter, out-bandcommunication will be largely described. Examples of out-bandcommunication may include NFC, Bluetooth, Bluetooth low energy (BLE),and the like.

Herein, the wireless power transmitter (100) may be provided as a fixedtype or a mobile (or portable) type. Examples of the fixed transmittertype may include an embedded type, which is embedded in in-door ceilingsor wall surfaces or embedded in furniture, such as tables, an implantedtype, which is installed in out-door parking lots, bus stops, subwaystations, and so on, or being installed in means of transportation, suchas vehicles or trains. The mobile (or portable) type wireless powertransmitter (100) may be implemented as a part of another device, suchas a mobile device having a portable size or weight or a cover of alaptop computer, and so on.

Additionally, the wireless power receiver (200) should be interpreted asa comprehensive concept including diverse home appliances and devicesthat are operated by being wirelessly supplied with power instead ofdiverse electronic devices being equipped with a battery and a powercable. Typical examples of the wireless power receiver (200) may includeportable terminals, cellular phones, smartphones, personal digitalassistants (PDAs), portable media players (PDPs), Wibro terminals,tablet PCs, phablet, laptop computers, digital cameras, navigationterminals, television, electronic vehicles (EVs), and so on.

FIG. 2 is a block diagram of a wireless power system (10) according toanother exemplary embodiment of the present disclosure.

Referring to FIG. 2 , In the wireless power system (10), one wirelesspower receiver (200) or a plurality of wireless power receivers mayexist. Although it is shown in FIG. 1 that the wireless powertransmitter (100) and the wireless power receiver (200) send and receivepower to and from one another in a one-to-one correspondence (orrelationship), as shown in FIG. 2 , it is also possible for one wirelesspower transmitter (100) to simultaneously transfer power to multiplewireless power receivers (200-1, 200-2, . . . , 200-M). Mostparticularly, in case the wireless power transfer (or transmission) isperformed by using a magnetic resonance method, one wireless powertransmitter (100) may transfer power to multiple wireless powerreceivers (200-1, 200-2, . . . , 200-M) by using a synchronizedtransport (or transfer) method or a time-division transport (ortransfer) method.

Additionally, although it is shown in FIG. 1 that the wireless powertransmitter (100) directly transfers (or transmits) power to thewireless power receiver (200), the wireless power system (10) may alsobe equipped with a separate wireless power transceiver, such as a relayor repeater, for increasing a wireless power transport distance betweenthe wireless power transmitter (100) and the wireless power receiver(200). In this case, power is delivered to the wireless powertransceiver from the wireless power transmitter (100), and, then, thewireless power transceiver may transfer the received power to thewireless power receiver (200).

Hereinafter, the terms wireless power receiver, power receiver, andreceiver, which are mentioned in this specification, will refer to thewireless power receiver (200). Also, the terms wireless powertransmitter, power transmitter, and transmitter, which are mentioned inthis specification, will refer to the wireless power transmitter (100).

FIG. 3 a shows an exemplary embodiment of diverse electronic devicesadopting a wireless power transfer system.

As shown in FIG. 3 a , the electronic devices included in the wirelesspower transfer system are sorted in accordance with the amount oftransmitted power and the amount of received power. Referring to FIG. 3a , wearable devices, such as smart watches, smart glasses, head mounteddisplays (HMDs), smart rings, and so on, and mobile electronic devices(or portable electronic devices), such as earphones, remote controllers,smartphones, PDAs, tablet PCs, and so on, may adopt a low-power(approximately 5 W or less or approximately 20 W or less) wirelesscharging method.

Small-sized/Mid-sized electronic devices, such as laptop computers,robot vacuum cleaners, TV receivers, audio devices, vacuum cleaners,monitors, and so on, may adopt a mid-power (approximately 50 W or lessor approximately 200 W or less) wireless charging method. Kitchenappliances, such as mixers, microwave ovens, electric rice cookers, andso on, and personal transportation devices (or other electric devices ormeans of transportation), such as powered wheelchairs, powered kickscooters, powered bicycles, electric cars, and so on may adopt ahigh-power (approximately 2 kW or less or approximately 22 kW or less)wireless charging method.

The electric devices or means of transportation, which are describedabove (or shown in FIG. 1 ) may each include a wireless power receiver,which will hereinafter be described in detail. Therefore, theabove-described electric devices or means of transportation may becharged (or re-charged) by wirelessly receiving power from a wirelesspower transmitter.

Hereinafter, although the present disclosure will be described based ona mobile device adopting the wireless power charging method, this ismerely exemplary. And, therefore, it shall be understood that thewireless charging method according to the present disclosure may beapplied to diverse electronic devices.

A standard for the wireless power transfer (or transmission) includes awireless power consortium (WPC), an air fuel alliance (AFA), and a powermatters alliance (PMA).

The WPC standard defines a baseline power profile (BPP) and an extendedpower profile (EPP). The BPP is related to a wireless power transmitterand a wireless power receiver supporting a power transfer of 5 W, andthe EPP is related to a wireless power transmitter and a wireless powerreceiver supporting the transfer of a power range greater than 5 W andless than 30 W.

Diverse wireless power transmitters and wireless power receivers eachusing a different power level may be covered by each standard and may besorted by different power classes or categories.

For example, the WPC may categorize (or sort) the wireless powertransmitters and the wireless power receivers as PC−1, PC0, PC1, andPC2, and the WPC may provide a standard document (or specification) foreach power class (PC). The PC−1 standard relates to wireless powertransmitters and receivers providing a guaranteed power of less than 5W. The application of PC−1 includes wearable devices, such as smartwatches.

The PC0 standard relates to wireless power transmitters and receiversproviding a guaranteed power of 5 W. The PC0 standard includes an EPPhaving a guaranteed power ranges that extends to 30 W. Although in-band(IB) communication corresponds to a mandatory communication protocol ofPC0, out-of-band (OB) communication that is used as an optional backupchannel may also be used for PC0. The wireless power receiver may beidentified by setting up an OB flag, which indicates whether or not theOB is supported, within a configuration packet. A wireless powertransmitter supporting the OB may enter an OB handover phase bytransmitting a bit-pattern for an OB handover as a response to theconfiguration packet. The response to the configuration packet maycorrespond to an NAK, an ND, or an 8-bit pattern that is newly defined.The application of the PC0 includes smartphones.

The PC1 standard relates to wireless power transmitters and receiversproviding a guaranteed power ranging from 30 W to 150 W. OB correspondsto a mandatory communication channel for PC1, and IB is used forinitialization and link establishment to OB. The wireless powertransmitter may enter an OB handover phase by transmitting a bit-patternfor an OB handover as a response to the configuration packet. Theapplication of the PC1 includes laptop computers or power tools.

The PC2 standard relates to wireless power transmitters and receiversproviding a guaranteed power ranging from 200 W to 2 kW, and itsapplication includes kitchen appliances.

As described above, the PCs may be differentiated in accordance with therespective power levels. And, information on whether or not thecompatibility between the same PCs is supported may be optional ormandatory. Herein, the compatibility between the same PCs indicates thatpower transfer/reception between the same PCs is possible. For example,in case a wireless power transmitter corresponding to PC x is capable ofperforming charging of a wireless power receiver having the same PC x,it may be understood that compatibility is maintained between the samePCs. Similarly, compatibility between different PCs may also besupported. Herein, the compatibility between different PCs indicatesthat power transfer/reception between different PCs is also possible.For example, in case a wireless power transmitter corresponding to PC xis capable of performing charging of a wireless power receiver having PCy, it may be understood that compatibility is maintained between thedifferent PCs.

The support of compatibility between PCs corresponds to an extremelyimportant issue in the aspect of user experience and establishment ofinfrastructure. Herein, however, diverse problems, which will bedescribed below, exist in maintaining the compatibility between PCs.

In case of the compatibility between the same PCs, for example, in caseof a wireless power receiver using a lap-top charging method, whereinstable charging is possible only when power is continuously transferred,even if its respective wireless power transmitter has the same PC, itmay be difficult for the corresponding wireless power receiver to stablyreceive power from a wireless power transmitter of the power toolmethod, which transfers power non-continuously. Additionally, in case ofthe compatibility between different PCs, for example, in case a wirelesspower transmitter having a minimum guaranteed power of 200 W transferspower to a wireless power receiver having a maximum guaranteed power of5 W, the corresponding wireless power receiver may be damaged due to anovervoltage. As a result, it may be inappropriate (or difficult) to usethe PS as an index/reference standard representing/indicating thecompatibility.

Wireless power transmitters and receivers may provide a very convenientuser experience and interface (UX/UI). That is, a smart wirelesscharging service may be provided, and the smart wireless chargingservice may be implemented based on a UX/UI of a smartphone including awireless power transmitter. For these applications, an interface betweena processor of a smartphone and a wireless charging receiver allows for“drop and play” two-way communication between the wireless powertransmitter and the wireless power receiver.

As an example, a user may experience a smart wireless charging servicein a hotel. When the user enters a hotel room and puts a smartphone on awireless charger in the room, the wireless charger transmits wirelesspower to the smartphone and the smartphone receives wireless power. Inthis process, the wireless charger transmits information on the smartwireless charging service to the smartphone. When it is detected thatthe smartphone is located on the wireless charger, when it is detectedthat wireless power is received, or when the smartphone receivesinformation on the smart wireless charging service from the wirelesscharger, the smartphone enters a state of inquiring the user aboutagreement (opt-in) of supplemental features. To this end, the smartphonemay display a message on a screen in a manner with or without an alarmsound. An example of the message may include the phrase “Welcome to ###hotel. Select “Yes” to activate smart charging functions: Yes|NoThanks.” The smartphone receives an input from the user who selects Yesor No Thanks, and performs a next procedure selected by the user. If Yesis selected, the smartphone transmits corresponding information to thewireless charger. The smartphone and the wireless charger perform thesmart charging function together.

The smart wireless charging service may also include receiving WiFicredentials auto-filled. For example, the wireless charger transmits theWiFi credentials to the smartphone, and the smartphone automaticallyinputs the WiFi credentials received from the wireless charger byrunning an appropriate application.

The smart wireless charging service may also include running a hotelapplication that provides hotel promotions or obtaining remotecheck-in/check-out and contact information.

As another example, the user may experience the smart wireless chargingservice in a vehicle. When the user gets in the vehicle and puts thesmartphone on the wireless charger, the wireless charger transmitswireless power to the smartphone and the smartphone receives wirelesspower. In this process, the wireless charger transmits information onthe smart wireless charging service to the smartphone. When it isdetected that the smartphone is located on the wireless charger, whenwireless power is detected to be received, or when the smartphonereceives information on the smart wireless charging service from thewireless charger, the smartphone enters a state of inquiring the userabout checking identity.

In this state, the smartphone is automatically connected to the vehiclevia WiFi and/or Bluetooth. The smartphone may display a message on thescreen in a manner with or without an alarm sound. An example of themessage may include a phrase of “Welcome to your car. Select “Yes” tosynch device with in-car controls: Yes|No Thanks.” Upon receiving theuser's input to select Yes or No Thanks, the smartphone performs a nextprocedure selected by the user. If Yes is selected, the smartphonetransmits corresponding information to the wireless charger. Inaddition, the smartphone and the wireless charger may run an in-vehiclesmart control function together by driving in-vehicleapplication/display software. The user may enjoy the desired music andcheck a regular map location. The in-vehicle applications/displaysoftware may include an ability to provide synchronous access forpassers-by.

As another example, the user may experience smart wireless charging athome. When the user enters the room and puts the smartphone on thewireless charger in the room, the wireless charger transmits wirelesspower to the smartphone and the smartphone receives wireless power. Inthis process, the wireless charger transmits information on the smartwireless charging service to the smartphone. When it is detected thatthe smartphone is located on the wireless charger, when wireless poweris detected to be received, or when the smartphone receives informationon the smart wireless charging service from the wireless charger, thesmartphone enters a state of inquiring the user about agreement (opt-in)of supplemental features. To this end, the smartphone may display amessage on the screen in a manner with or without an alarm sound. Anexample of the message may include a phrase such as “Hi xxx, Would youlike to activate night mode and secure the building?: Yes|No Thanks.”The smartphone receives a user input to select Yes or No Thanks andperforms a next procedure selected by the user. If Yes is selected, thesmartphone transmits corresponding information to the wireless charger.The smartphones and the wireless charger may recognize at least user'spattern and recommend the user to lock doors and windows, turn offlights, or set an alarm.

Hereinafter, ‘profiles’ will be newly defined based on indexes/referencestandards representing/indicating the compatibility. More specifically,it may be understood that by maintaining compatibility between wirelesspower transmitters and receivers having the same ‘profile’, stable powertransfer/reception may be performed, and that power transfer/receptionbetween wireless power transmitters and receivers having different‘profiles’ cannot be performed. The ‘profiles’ may be defined inaccordance with whether or not compatibility is possible and/or theapplication regardless of (or independent from) the power class.

For example, the profile may be sorted into 3 different categories, suchas i) Mobile, ii) Power tool and iii) Kitchen.

For another example, the profile may be sorted into 4 differentcategories, such as i) Mobile, ii) Power tool, iii) Kitchen, and iv)Wearable.

In case of the ‘Mobile’ profile, the PC may be defined as PC0 and/orPC1, the communication protocol/method may be defined as IB and OBcommunication, and the operation frequency may be defined as 87 to 205kHz, and smartphones, laptop computers, and so on, may exist as theexemplary application.

In case of the ‘Power tool’ profile, the PC may be defined as PC1, thecommunication protocol/method may be defined as IB communication, andthe operation frequency may be defined as 87 to 145 kHz, and powertools, and so on, may exist as the exemplary application.

In case of the ‘Kitchen’ profile, the PC may be defined as PC2, thecommunication protocol/method may be defined as NFC-based communication,and the operation frequency may be defined as less than 100 kHz, andkitchen/home appliances, and so on, may exist as the exemplaryapplication.

In the case of power tools and kitchen profiles, NFC communication maybe used between the wireless power transmitter and the wireless powerreceiver. The wireless power transmitter and the wireless power receivermay confirm that they are NFC devices with each other by exchanging WPCNFC data exchange profile format (NDEF).

FIG. 3 b shows an example of a WPC NDEF in a wireless power transfersystem.

Referring to FIG. 3 b , the WPC NDEF may include, for example, anapplication profile field (e.g., 1B), a version field (e.g., 1B), andprofile specific data (e.g., 1B). The application profile fieldindicates whether the corresponding device is i) mobile and computing,ii) power tool, and iii) kitchen, and an upper nibble in the versionfield indicates a major version and a lower nibble indicates a minorversion. In addition, profile-specific data defines content for thekitchen.

In case of the ‘Wearable’ profile, the PC may be defined as PC−1, thecommunication protocol/method may be defined as IB communication, andthe operation frequency may be defined as 87 to 205 kHz, and wearabledevices that are worn by the users, and so on, may exist as theexemplary application.

It may be mandatory to maintain compatibility between the same profiles,and it may be optional to maintain compatibility between differentprofiles.

The above-described profiles (Mobile profile, Power tool profile,Kitchen profile, and Wearable profile) may be generalized and expressedas first to nth profile, and a new profile may be added/replaced inaccordance with the WPC standard and the exemplary embodiment.

In case the profile is defined as described above, the wireless powertransmitter may optionally perform power transfer only to the wirelesspower receiving corresponding to the same profile as the wireless powertransmitter, thereby being capable of performing a more stable powertransfer. Additionally, since the load (or burden) of the wireless powertransmitter may be reduced and power transfer is not attempted to awireless power receiver for which compatibility is not possible, therisk of damage in the wireless power receiver may be reduced.

PC1 of the ‘Mobile’ profile may be defined by being derived from anoptional extension, such as OB, based on PC0. And, the ‘Power tool’profile may be defined as a simply modified version of the PC1 ‘Mobile’profile. Additionally, up until now, although the profiles have beendefined for the purpose of maintaining compatibility between the sameprofiles, in the future, the technology may be evolved to a level ofmaintaining compatibility between different profiles. The wireless powertransmitter or the wireless power receiver may notify (or announce) itsprofile to its counterpart by using diverse methods.

In the AFA standard, the wireless power transmitter is referred to as apower transmitting unit (PTU), and the wireless power receiver isreferred to as a power receiving unit (PRU). And, the PTU is categorizedto multiple classes, as shown in Table 1, and the PRU is categorized tomultiple classes, as shown in Table 2.

TABLE 1 Minimum Minimum value category for a maximum support number ofPTU P_(TX)_IN_MAX requirement supported devices Class 1  2W 1× Category1 1× Category 1 Class 2 10W 1× Category 3 2× Category 2 Class 3 16W 1×Category 4 2× Category 3 Class 4 33W 1× Category 5 3× Category 3 Class 550W 1× Category 6 4× Category 3 Class 6 70W 1× Category 7 5× Category 3

TABLE 2 PRU P_(RX)_OUT_MAX' Exemplary application Category 1 TBDBluetooth headset Category 2 3.5 W Feature phone Category 3 6.5 WSmartphone Category 4  13 W Tablet PC, Phablet Category 5  25 W Smallform factor laptop Category 6 37.5 W General laptop Category 7  50 WHome appliance

As shown in Table 1, a maximum output power capability of Class n PTUmay be equal to or greater than the P_(TX_IN_MAX) of the correspondingclass. The PRU cannot draw a power that is higher than the power levelspecified in the corresponding category.

FIG. 4 is a block diagram of a wireless power transfer system accordingto another exemplary embodiment of the present disclosure.

Referring to FIG. 4 , the wireless power transfer system (10) includes amobile device (450), which wirelessly receives power, and a base station(400), which wirelessly transmits power.

As a device providing induction power or resonance power, the basestation (400) may include at least one of a wireless power transmitter(100) and a system unit (405). The wireless power transmitter (100) maytransmit induction power or resonance power and may control thetransmission. The wireless power transmitter (100) may include a powerconversion unit (110) converting electric energy to a power signal bygenerating a magnetic field through a primary coil (or primary coils),and a communications & control unit (120) controlling the communicationand power transfer between the wireless power receiver (200) in order totransfer power at an appropriate (or suitable) level. The system unit(405) may perform input power provisioning, controlling of multiplewireless power transmitters, and other operation controls of the basestation (400), such as user interface control.

The primary coil may generate an electromagnetic field by using analternating current power (or voltage or current). The primary coil issupplied with an alternating current power (or voltage or current) of aspecific frequency, which is being outputted from the power conversionunit (110). And, accordingly, the primary coil may generate a magneticfield of the specific frequency. The magnetic field may be generated ina non-radial shape or a radial shape. And, the wireless power receiver(200) receives the generated magnetic field and then generates anelectric current. In other words, the primary coil wirelessly transmitspower.

In the magnetic induction method, a primary coil and a secondary coilmay have randomly appropriate shapes. For example, the primary coil andthe secondary coil may correspond to copper wire being wound around ahigh-permeability formation, such as ferrite or a non-crystalline metal.The primary coil may also be referred to as a transmitting coil, aprimary core, a primary winding, a primary loop antenna, and so on.Meanwhile, the secondary coil may also be referred to as a receivingcoil, a secondary core, a secondary winding, a secondary loop antenna, apickup antenna, and so on.

In case of using the magnetic resonance method, the primary coil and thesecondary coil may each be provided in the form of a primary resonanceantenna and a secondary resonance antenna. The resonance antenna mayhave a resonance structure including a coil and a capacitor. At thispoint, the resonance frequency of the resonance antenna may bedetermined by the inductance of the coil and a capacitance of thecapacitor. Herein, the coil may be formed to have a loop shape. And, acore may be placed inside the loop. The core may include a physicalcore, such as a ferrite core, or an air core.

The energy transmission (or transfer) between the primary resonanceantenna and the second resonance antenna may be performed by a resonancephenomenon occurring in the magnetic field. When a near fieldcorresponding to a resonance frequency occurs in a resonance antenna,and in case another resonance antenna exists near the correspondingresonance antenna, the resonance phenomenon refers to a highly efficientenergy transfer occurring between the two resonance antennas that arecoupled with one another. When a magnetic field corresponding to theresonance frequency is generated between the primary resonance antennaand the secondary resonance antenna, the primary resonance antenna andthe secondary resonance antenna resonate with one another. And,accordingly, in a general case, the magnetic field is focused toward thesecond resonance antenna at a higher efficiency as compared to a casewhere the magnetic field that is generated from the primary antenna isradiated to a free space. And, therefore, energy may be transferred tothe second resonance antenna from the first resonance antenna at a highefficiency. The magnetic induction method may be implemented similarlyto the magnetic resonance method. However, in this case, the frequencyof the magnetic field is not required to be a resonance frequency.Nevertheless, in the magnetic induction method, the loops configuringthe primary coil and the secondary coil are required to match oneanother, and the distance between the loops should be very close-ranged.

Although it is not shown in the drawing, the wireless power transmitter(100) may further include a communication antenna. The communicationantenna may transmit and/or receive a communication signal by using acommunication carrier apart from the magnetic field communication. Forexample, the communication antenna may transmit and/or receivecommunication signals corresponding to Wi-Fi, Bluetooth, Bluetooth LE,ZigBee, NFC, and so on.

The communications & control unit (120) may transmit and/or receiveinformation to and from the wireless power receiver (200). Thecommunications & control unit (120) may include at least one of an TBcommunication module and an OB communication module.

The TB communication module may transmit and/or receive information byusing a magnetic wave, which uses a specific frequency as its centerfrequency. For example, the communications & control unit (120) mayperform in-band (TB) communication by transmitting communicationinformation on the operating frequency of wireless power transferthrough the primary coil or by receiving communication information onthe operating frequency through the primary coil. At this point, thecommunications & control unit (120) may load information in the magneticwave or may interpret the information that is carried by the magneticwave by using a modulation scheme, such as binary phase shift keying(BPSK), Frequency Shift Keying (FSK) or amplitude shift keying (ASK),and so on, or a coding scheme, such as Manchester coding ornon-return-to-zero level (NZR-L) coding, and so on. By using theabove-described TB communication, the communications & control unit(120) may transmit and/or receive information to distances of up toseveral meters at a data transmission rate of several kbps.

The OB communication module may also perform out-of-band communicationthrough a communication antenna. For example, the communications &control unit (120) may be provided to a near field communication module.Examples of the near field communication module may includecommunication modules, such as Wi-Fi, Bluetooth, Bluetooth LE, ZigBee,NFC, and so on.

The communications & control unit (120) may control the overalloperations of the wireless power transmitter (100). The communications &control unit (120) may perform calculation and processing of diverseinformation and may also control each configuration element of thewireless power transmitter (100).

The communications & control unit (120) may be implemented in a computeror a similar device as hardware, software, or a combination of the same.When implemented in the form of hardware, the communications & controlunit (120) may be provided as an electronic circuit performing controlfunctions by processing electrical signals. And, when implemented in theform of software, the communications & control unit (120) may beprovided as a program that operates the communications & control unit(120).

By controlling the operating point, the communications & control unit(120) may control the transmitted power. The operating point that isbeing controlled may correspond to a combination of a frequency (orphase), a duty cycle, a duty ratio, and a voltage amplitude. Thecommunications & control unit (120) may control the transmitted power byadjusting any one of the frequency (or phase), the duty cycle, the dutyratio, and the voltage amplitude. Additionally, the wireless powertransmitter (100) may supply a consistent level of power, and thewireless power receiver (200) may control the level of received power bycontrolling the resonance frequency.

The mobile device (450) includes a wireless power receiver (200)receiving wireless power through a secondary coil, and a load (455)receiving and storing the power that is received by the wireless powerreceiver (200) and supplying the received power to the device.

The wireless power receiver (200) may include a power pick-up unit (210)and a communications & control unit (220). The power pick-up unit (210)may receive wireless power through the secondary coil and may convertthe received wireless power to electric energy. The power pick-up unit(210) rectifies the alternating current (AC) signal, which is receivedthrough the secondary coil, and converts the rectified signal to adirect current (DC) signal. The communications & control unit (220) maycontrol the transmission and reception of the wireless power (transferand reception of power).

The secondary coil may receive wireless power that is being transmittedfrom the wireless power transmitter (100). The secondary coil mayreceive power by using the magnetic field that is generated in theprimary coil. Herein, in case the specific frequency corresponds aresonance frequency, magnetic resonance may occur between the primarycoil and the secondary coil, thereby allowing power to be transferredwith greater efficiency.

Although it is not shown in FIG. 4 a , the communications & control unit(220) may further include a communication antenna. The communicationantenna may transmit and/or receive a communication signal by using acommunication carrier apart from the magnetic field communication. Forexample, the communication antenna may transmit and/or receivecommunication signals corresponding to Wi-Fi, Bluetooth, Bluetooth LE,ZigBee, NFC, and so on.

The communications & control unit (220) may transmit and/or receiveinformation to and from the wireless power transmitter (100). Thecommunications & control unit (220) may include at least one of an IBcommunication module and an OB communication module.

The IB communication module may transmit and/or receive information byusing a magnetic wave, which uses a specific frequency as its centerfrequency. For example, the communications & control unit (220) mayperform IB communication by loading information in the magnetic wave andby transmitting the information through the secondary coil or byreceiving a magnetic wave carrying information through the secondarycoil. At this point, the communications & control unit (120) may loadinformation in the magnetic wave or may interpret the information thatis carried by the magnetic wave by using a modulation scheme, such asbinary phase shift keying (BPSK), Frequency Shift Keying (FSK) oramplitude shift keying (ASK), and so on, or a coding scheme, such asManchester coding or non-return-to-zero level (NZR-L) coding, and so on.By using the above-described IB communication, the communications &control unit (220) may transmit and/or receive information to distancesof up to several meters at a data transmission rate of several kbps.

The OB communication module may also perform out-of-band communicationthrough a communication antenna. For example, the communications &control unit (220) may be provided to a near field communication module.

Examples of the near field communication module may includecommunication modules, such as Wi-Fi, Bluetooth, Bluetooth LE, ZigBee,NFC, and so on.

The communications & control unit (220) may control the overalloperations of the wireless power receiver (200). The communications &control unit (220) may perform calculation and processing of diverseinformation and may also control each configuration element of thewireless power receiver (200).

The communications & control unit (220) may be implemented in a computeror a similar device as hardware, software, or a combination of the same.When implemented in the form of hardware, the communications & controlunit (220) may be provided as an electronic circuit performing controlfunctions by processing electrical signals. And, when implemented in theform of software, the communications & control unit (220) may beprovided as a program that operates the communications & control unit(220).

Hereinafter, the coil or coil unit includes a coil and at least onedevice being approximate to the coil, and the coil or coil unit may alsobe referred to as a coil assembly, a coil cell, or a cell.

FIG. 5 is a state transition diagram for describing a wireless powertransfer procedure.

Referring to FIG. 5 , the power transfer (or transfer) from the wirelesspower transmitter to the wireless power receiver according to anexemplary embodiment of the present disclosure may be broadly dividedinto a selection phase (510), a ping phase (520), an identification andconfiguration phase (530), a negotiation phase (540), a calibrationphase (550), a power transfer phase (560), and a renegotiation phase(570).

If a specific error or a specific event is detected when the powertransfer is initiated or while maintaining the power transfer, theselection phase (510) may include a shifting phase (or step)—referencenumerals S502, S504, S508, S510, and S512. Herein, the specific error orspecific event will be specified in the following description.Additionally, during the selection phase (510), the wireless powertransmitter may monitor whether or not an object exists on an interfacesurface. If the wireless power transmitter detects that an object isplaced on the interface surface, the process step may be shifted to theping phase (520). During the selection phase (510), the wireless powertransmitter may transmit an analog ping having a power signal (or apulse) corresponding to an extremely short duration, and may detectwhether or not an object exists within an active area of the interfacesurface based on a current change in the transmitting coil or theprimary coil.

In case an object is sensed (or detected) in the selection phase (510),the wireless power transmitter may measure a quality factor of awireless power resonance circuit (e.g., power transfer coil and/orresonance capacitor). According to the exemplary embodiment of thepresent disclosure, during the selection phase (510), the wireless powertransmitter may measure the quality factor in order to determine whetheror not a foreign object exists in the charging area along with thewireless power receiver. In the coil that is provided in the wirelesspower transmitter, inductance and/or components of the series resistancemay be reduced due to a change in the environment, and, due to suchdecrease, a value of the quality factor may also be decreased. In orderto determine the presence or absence of a foreign object by using themeasured quality factor value, the wireless power transmitter mayreceive from the wireless power receiver a reference quality factorvalue, which is measured in advance in a state where no foreign objectis placed within the charging area. The wireless power transmitter maydetermine the presence or absence of a foreign object by comparing themeasured quality factor value with the reference quality factor value,which is received during the negotiation phase (540). However, in caseof a wireless power receiver having a low reference quality factorvalue—e.g., depending upon its type, purpose, characteristics, and soon, the wireless power receiver may have a low reference quality factorvalue—in case a foreign object exists, since the difference between thereference quality factor value and the measured quality factor value issmall (or insignificant), a problem may occur in that the presence ofthe foreign object cannot be easily determined. Accordingly, in thiscase, other determination factors should be further considered, or thepresent or absence of a foreign object should be determined by usinganother method.

According to another exemplary embodiment of the present disclosure, incase an object is sensed (or detected) in the selection phase (510), inorder to determine whether or not a foreign object exists in thecharging area along with the wireless power receiver, the wireless powertransmitter may measure the quality factor value within a specificfrequency area (e.g., operation frequency area). In the coil that isprovided in the wireless power transmitter, inductance and/or componentsof the series resistance may be reduced due to a change in theenvironment, and, due to such decrease, the resonance frequency of thecoil of the wireless power transmitter may be changed (or shifted). Morespecifically, a quality factor peak frequency that corresponds to afrequency in which a maximum quality factor value is measured within theoperation frequency band may be moved (or shifted).

In the ping phase (520), if the wireless power transmitter detects thepresence of an object, the transmitter activates (or Wakes up) areceiver and transmits a digital ping for identifying whether or not thedetected object corresponds to the wireless power receiver. During theping phase (520), if the wireless power transmitter fails to receive aresponse signal for the digital ping—e.g., a signal intensitypacket—from the receiver, the process may be shifted back to theselection phase (510). Additionally, in the ping phase (520), if thewireless power transmitter receives a signal indicating the completionof the power transfer—e.g., charging complete packet—from the receiver,the process may be shifted back to the selection phase (510).

If the ping phase (520) is completed, the wireless power transmitter mayshift to the identification and configuration phase (530) foridentifying the receiver and for collecting configuration and statusinformation.

In the identification and configuration phase (530), if the wirelesspower transmitter receives an unwanted packet (i.e., unexpected packet),or if the wireless power transmitter fails to receive a packet during apredetermined period of time (i.e., out of time), or if a packettransmission error occurs (i.e., transmission error), or if a powertransfer contract is not configured (i.e., no power transfer contract),the wireless power transmitter may shift to the selection phase (510).

The wireless power transmitter may confirm (or verify) whether or notits entry to the negotiation phase (540) is needed based on aNegotiation field value of the configuration packet, which is receivedduring the identification and configuration phase (530). Based on theverified result, in case a negotiation is needed, the wireless powertransmitter enters the negotiation phase (540) and may then perform apredetermined FOD detection procedure. Conversely, in case a negotiationis not needed, the wireless power transmitter may immediately enter thepower transfer phase (560).

In the negotiation phase (540), the wireless power transmitter mayreceive a Foreign Object Detection (FOD) status packet that includes areference quality factor value. Or, the wireless power transmitter mayreceive an FOD status packet that includes a reference peak frequencyvalue. Alternatively, the wireless power transmitter may receive astatus packet that includes a reference quality factor value and areference peak frequency value. At this point, the wireless powertransmitter may determine a quality coefficient threshold value for FOdetection based on the reference quality factor value. The wirelesspower transmitter may determine a peak frequency threshold value for FOdetection based on the reference peak frequency value.

The wireless power transmitter may detect the presence or absence of anFO in the charging area by using the determined quality coefficientthreshold value for FO detection and the currently measured qualityfactor value (i.e., the quality factor value that was measured beforethe ping phase), and, then, the wireless power transmitter may controlthe transmitted power in accordance with the FO detection result. Forexample, in case the FO is detected, the power transfer may be stopped.However, the present disclosure will not be limited only to this.

The wireless power transmitter may detect the presence or absence of anFO in the charging area by using the determined peak frequency thresholdvalue for FO detection and the currently measured peak frequency value(i.e., the peak frequency value that was measured before the pingphase), and, then, the wireless power transmitter may control thetransmitted power in accordance with the FO detection result. Forexample, in case the FO is detected, the power transfer may be stopped.However, the present disclosure will not be limited only to this.

In case the FO is detected, the wireless power transmitter may return tothe selection phase (510). Conversely, in case the FO is not detected,the wireless power transmitter may proceed to the calibration phase(550) and may, then, enter the power transfer phase (560). Morespecifically, in case the FO is not detected, the wireless powertransmitter may determine the intensity of the received power that isreceived by the receiving end during the calibration phase (550) and maymeasure power loss in the receiving end and the transmitting end inorder to determine the intensity of the power that is transmitted fromthe transmitting end. In other words, during the calibration phase(550), the wireless power transmitter may estimate the power loss basedon a difference between the transmitted power of the transmitting endand the received power of the receiving end. The wireless powertransmitter according to the exemplary embodiment of the presentdisclosure may calibrate the threshold value for the FOD detection byapplying the estimated power loss.

In the power transfer phase (560), in case the wireless powertransmitter receives an unwanted packet (i.e., unexpected packet), or incase the wireless power transmitter fails to receive a packet during apredetermined period of time (i.e., time-out), or in case a violation ofa predetermined power transfer contract occurs (i.e., power transfercontract violation), or in case charging is completed, the wirelesspower transmitter may shift to the selection phase (510).

Additionally, in the power transfer phase (560), in case the wirelesspower transmitter is required to reconfigure the power transfer contractin accordance with a status change in the wireless power transmitter,the wireless power transmitter may shift to the renegotiation phase(570). At this point, if the renegotiation is successfully completed,the wireless power transmitter may return to the power transfer phase(560).

In this embodiment, the calibration step 550 and the power transferphase 560 are divided into separate steps, but the calibration step 550may be integrated into the power transfer phase 560. In this case,operations in the calibration step 550 may be performed in the powertransfer phase 560.

The above-described power transfer contract may be configured based onthe status and characteristic information of the wireless powertransmitter and receiver. For example, the wireless power transmitterstatus information may include information on a maximum amount oftransmittable power, information on a maximum number of receivers thatmay be accommodated, and so on. And, the receiver status information mayinclude information on the required power, and so on.

FIG. 6 shows a power control method according to an exemplary embodimentof the present disclosure.

As shown in FIG. 6 , in the power transfer phase (560), by alternatingthe power transfer and/or reception and communication, the wirelesspower transmitter (100) and the wireless power receiver (200) maycontrol the amount (or size) of the power that is being transferred. Thewireless power transmitter and the wireless power receiver operate at aspecific control point. The control point indicates a combination of thevoltage and the electric current that are provided from the output ofthe wireless power receiver, when the power transfer is performed.

More specifically, the wireless power receiver selects a desired controlpoint, a desired output current/voltage, a temperature at a specificlocation of the mobile device, and so on, and additionally determines anactual control point at which the receiver is currently operating. Thewireless power receiver calculates a control error value by using thedesired control point and the actual control point, and, then, thewireless power receiver may transmit the calculated control error valueto the wireless power transmitter as a control error packet.

Also, the wireless power transmitter may configure/control a newoperating point—amplitude, frequency, and duty cycle—by using thereceived control error packet, so as to control the power transfer.Therefore, the control error packet may be transmitted/received at aconstant time interval during the power transfer phase, and, accordingto the exemplary embodiment, in case the wireless power receiverattempts to reduce the electric current of the wireless powertransmitter, the wireless power receiver may transmit the control errorpacket by setting the control error value to a negative number. And, incase the wireless power receiver intends to increase the electriccurrent of the wireless power transmitter, the wireless power receivertransmit the control error packet by setting the control error value toa positive number. During the induction mode, by transmitting thecontrol error packet to the wireless power transmitter as describedabove, the wireless power receiver may control the power transfer.

In the resonance mode, which will hereinafter be described in detail,the device may be operated by using a method that is different from theinduction mode. In the resonance mode, one wireless power transmittershould be capable of serving a plurality of wireless power receivers atthe same time. However, in case of controlling the power transfer justas in the induction mode, since the power that is being transferred iscontrolled by a communication that is established with one wirelesspower receiver, it may be difficult to control the power transfer ofadditional wireless power receivers. Therefore, in the resonance modeaccording to the present disclosure, a method of controlling the amountof power that is being received by having the wireless power transmittercommonly transfer (or transmit) the basic power and by having thewireless power receiver control its own resonance frequency.Nevertheless, even during the operation of the resonance mode, themethod described above in FIG. 6 will not be completely excluded. And,additional control of the transmitted power may be performed by usingthe method of FIG. 6 .

FIG. 7 is a block diagram of a wireless power transmitter according toanother exemplary embodiment of the present disclosure. This may belongto a wireless power transfer system that is being operated in themagnetic resonance mode or the shared mode. The shared mode may refer toa mode performing a several-for-one (or one-to-many) communication andcharging between the wireless power transmitter and the wireless powerreceiver. The shared mode may be implemented as a magnetic inductionmethod or a resonance method.

Referring to FIG. 7 , the wireless power transmitter (700) may includeat least one of a cover (720) covering a coil assembly, a power adapter(730) supplying power to the power transmitter (740), a powertransmitter (740) transmitting wireless power, and a user interface(750) providing information related to power transfer processing andother related information. Most particularly, the user interface (750)may be optionally included or may be included as another user interface(750) of the wireless power transmitter (700).

The power transmitter (740) may include at least one of a coil assembly(760), an impedance matching circuit (770), an inverter (780), acommunication unit (790), and a control unit (710).

The coil assembly (760) includes at least one primary coil generating amagnetic field. And, the coil assembly (760) may also be referred to asa coil cell.

The impedance matching circuit (770) may provide impedance matchingbetween the inverter and the primary coil(s). The impedance matchingcircuit (770) may generate resonance from a suitable frequency thatboosts the electric current of the primary coil(s). In a multi-coilpower transmitter (740), the impedance matching circuit may additionallyinclude a multiplex that routes signals from the inverter to a subset ofthe primary coils. The impedance matching circuit may also be referredto as a tank circuit.

The impedance matching circuit (770) may include a capacitor, aninductor, and a switching device that switches the connection betweenthe capacitor and the inductor. The impedance matching may be performedby detecting a reflective wave of the wireless power that is beingtransferred (or transmitted) through the coil assembly (760) and byswitching the switching device based on the detected reflective wave,thereby adjusting the connection status of the capacitor or the inductoror adjusting the capacitance of the capacitor or adjusting theinductance of the inductor. In some cases, the impedance matching may becarried out even though the impedance matching circuit (770) is omitted.This specification also includes an exemplary embodiment of the wirelesspower transmitter (700), wherein the impedance matching circuit (770) isomitted.

The inverter (780) may convert a DC input to an AC signal. The inverter(780) may be operated as a half-bridge inverter or a full-bridgeinverter in order to generate a pulse wave and a duty cycle of anadjustable frequency. Additionally, the inverter may include a pluralityof stages in order to adjust input voltage levels.

The communication unit (790) may perform communication with the powerreceiver. The power receiver performs load modulation in order tocommunicate requests and information corresponding to the powertransmitter. Therefore, the power transmitter (740) may use thecommunication unit (790) so as to monitor the amplitude and/or phase ofthe electric current and/or voltage of the primary coil in order todemodulate the data being transmitted from the power receiver.

Additionally, the power transmitter (740) may control the output powerto that the data may be transferred through the communication unit (790)by using a Frequency Shift Keying (FSK) method, and so on.

The control unit (710) may control communication and power transfer (ordelivery) of the power transmitter (740). The control unit (710) maycontrol the power transfer by adjusting the above-described operatingpoint. The operating point may be determined by, for example, at leastany one of the operation frequency, the duty cycle, and the inputvoltage.

The communication unit (790) and the control unit (710) may each beprovided as a separate unit/device/chipset or may be collectivelyprovided as one unit/device/chipset.

FIG. 8 shows a wireless power receiver according to another exemplaryembodiment of the present disclosure. This may belong to a wirelesspower transfer system that is being operated in the magnetic resonancemode or the shared mode.

Referring to FIG. 8 , the wireless power receiver (800) may include atleast one of a user interface (820) providing information related topower transfer processing and other related information, a powerreceiver (830) receiving wireless power, a load circuit (840), and abase (850) supporting and covering the coil assembly. Most particularly,the user interface (820) may be optionally included or may be includedas another user interface (820) of the wireless power receiver (800).

The power receiver (830) may include at least one of a power converter(860), an impedance matching circuit (870), a coil assembly (880), acommunication unit (890), and a control unit (810).

The power converter (860) may convert the AC power that is received fromthe secondary coil to a voltage and electric current that are suitablefor the load circuit. According to an exemplary embodiment, the powerconverter (860) may include a rectifier. The rectifier may rectify thereceived wireless power and may convert the power from an alternatingcurrent (AC) to a direct current (DC). The rectifier may convert thealternating current to the direct current by using a diode or atransistor, and, then, the rectifier may smooth the converted current byusing the capacitor and resistance. Herein, a full-wave rectifier, ahalf-wave rectifier, a voltage multiplier, and so on, that areimplemented as a bridge circuit may be used as the rectifier.Additionally, the power converter may adapt a reflected impedance of thepower receiver.

The impedance matching circuit (870) may provide impedance matchingbetween a combination of the power converter (860) and the load circuit(840) and the secondary coil. According to an exemplary embodiment, theimpedance matching circuit may generate a resonance of approximately 100kHz, which may reinforce the power transfer. The impedance matchingcircuit (870) may include a capacitor, an inductor, and a switchingdevice that switches the combination of the capacitor and the inductor.The impedance matching may be performed by controlling the switchingdevice of the circuit that configured the impedance matching circuit(870) based on the voltage value, electric current value, power value,frequency value, and so on, of the wireless power that is beingreceived. In some cases, the impedance matching may be carried out eventhough the impedance matching circuit (870) is omitted. Thisspecification also includes an exemplary embodiment of the wirelesspower receiver (200), wherein the impedance matching circuit (870) isomitted.

The coil assembly (880) includes at least one secondary coil, and,optionally, the coil assembly (880) may further include an elementshielding the metallic part of the receiver from the magnetic field.

The communication unit (890) may perform load modulation in order tocommunicate requests and other information to the power transmitter.

For this, the power receiver (830) may perform switching of theresistance or capacitor so as to change the reflected impedance.

The control unit (810) may control the received power. For this, thecontrol unit (810) may determine/calculate a difference between anactual operating point and a target operating point of the powerreceiver (830). Thereafter, by performing a request for adjusting thereflected impedance of the power transmitter and/or for adjusting anoperating point of the power transmitter, the difference between theactual operating point and the target operating point may beadjusted/reduced. In case of minimizing this difference, an optimalpower reception may be performed.

The communication unit (890) and the control unit (810) may each beprovided as a separate device/chipset or may be collectively provided asone device/chipset.

FIG. 9 shows operation statuses of a wireless power transmitter and awireless power receiver in a shared mode according to an exemplaryembodiment of the present disclosure.

Referring to FIG. 9 , the wireless power receiver operating in theshared mode may be operated in any one of a selection phase (1100), anintroduction phase (1110), a configuration phase (1120), a negotiationphase (1130), and a power transfer phase (1140).

Firstly, the wireless power transmitter according to the exemplaryembodiment of the present disclosure may transmit a wireless powersignal in order to detect the wireless power receiver. Morespecifically, a process of detecting a wireless power receiver by usingthe wireless power signal may be referred to as an Analog ping.

Meanwhile, the wireless power receiver that has received the wirelesspower signal may enter the selection phase (1100). As described above,the wireless power receiver that has entered the selection phase (1100)may detect the presence or absence of an FSK signal within the wirelesspower signal.

In other words, the wireless power receiver may perform communication byusing any one of an exclusive mode and a shared mode in accordance withthe presence or absence of the FSK signal.

More specifically, in case the FSK signal is included in the wirelesspower signal, the wireless power receiver may operate in the sharedmode, and, otherwise, the wireless power receiver may operate in theexclusive mode.

In case the wireless power receiver operates in the shared mode, thewireless power receiver may enter the introduction phase (1110). In theintroduction phase (1110), the wireless power receiver may transmit acontrol information (CI) packet to the wireless power transmitter inorder to transmit the control information packet during theconfiguration phase, the negotiation phase, and the power transferphase. The control information packet may have a header and informationrelated to control. For example, in the control information packet, theheader may correspond to 0X53.

In the introduction phase (1110), the wireless power receiver performsan attempt to request a free slot for transmitting the controlinformation (CI) packet during the following configuration phase,negotiation phase, and power transfer phase. At this point, the wirelesspower receiver selects a free slot and transmits an initial CI packet.If the wireless power transmitter transmits an ACK as a response to thecorresponding CI packet, the wireless power receiver enters theconfiguration phase. If the wireless power transmitter transmits a NAKas a response to the corresponding CI packet, this indicates thatanother wireless power receiver is performing communication through theconfiguration and negotiation phase. In this case, the wireless powerreceiver re-attempts to perform a request for a free slot.

If the wireless power receiver receives an ACK as a response to the CIpacket, the wireless power receiver may determine the position of aprivate slot within the frame by counting the remaining sync slots up tothe initial frame sync. In all of the subsequent slot-based frames, thewireless power receiver transmits the CI packet through thecorresponding slot.

If the wireless power transmitter authorizes the entry of the wirelesspower receiver to the configuration phase, the wireless powertransmitter provides a locked slot series for the exclusive usage of thewireless power receiver. This may ensure the wireless power receiver toproceed to the configuration phase without any collision.

The wireless power receiver transmits sequences of data packets, such astwo identification data packets (IDHI and IDLO), by using the lockedslots. When this phase is completed, the wireless power receiver entersthe negotiation phase. During the negotiation state, the wireless powertransmitter continues to provide the locked slots for the exclusiveusage of the wireless power receiver. This may ensure the wireless powerreceiver to proceed to the negotiation phase without any collision.

The wireless power receiver transmits one or more negotiation datapackets by using the corresponding locked slot, and the transmittednegotiation data packet(s) may be mixed with the private data packets.Eventually, the corresponding sequence is ended (or completed) alongwith a specific request (SRQ) packet. When the corresponding sequence iscompleted, the wireless power receiver enters the power transfer phase,and the wireless power transmitter stops the provision of the lockedslots.

In the power transfer phase, the wireless power receiver performs thetransmission of a CI packet by using the allocated slots and thenreceives the power. The wireless power receiver may include a regulatorcircuit. The regulator circuit may be included in acommunication/control unit. The wireless power receiver mayself-regulate a reflected impedance of the wireless power receiverthrough the regulator circuit. In other words, the wireless powerreceiver may adjust the impedance that is being reflected for an amountof power that is requested by an external load. This may prevent anexcessive reception of power and overheating.

In the shared mode, (depending upon the operation mode) since thewireless power transmitter may not perform the adjustment of power as aresponse to the received CI packet, in this case, control may be neededin order to prevent an overvoltage state.

Hereinafter, authentication between a wireless power transmitting deviceand a wireless power receiving device will be disclosed.

Suppose a foreign object lies between a wireless power receiving deviceand a wireless power transmitting device when the wireless powertransmitting device transmits wireless power to the wireless powerreceiving device. In this case, the foreign object absorbs part of themagnetic field. In other words, the foreign object receives part of thewireless power transmitted by the wireless power transmitting device,and the wireless power receiving device receives the remaining wirelesspower. In terms of power transmission efficiency, as much transmissionpower is lost as the power or energy absorbed by the foreign object. Asdescribed above, since a causal relationship may be established betweenthe existence of a foreign object and a power loss (P_(loss)), thewireless power transmitting device may detect the foreign object basedon how much power loss occurs. The foreign object detection method abovemay be referred to as a power loss-based foreign object detectionmethod.

The power lost due to the foreign object may be defined as a valueobtained by subtracting actual power received by the wireless powerreceiving device (P_(received)) from the power transmitted by thewireless power transmitting device (P_(transmitted)). Since the wirelesspower transmitting device already knows the power (P_(transmitted)) thatit has transmitted, the power loss may be calculated once the wirelesspower transmitting device knows the actual power received by thewireless power receiving device (P_(received)). To this end, thewireless power receiving device may periodically transmit a receivedpower data packet (RP) to the wireless power transmitting device toinform the wireless power transmitting device of the power received bythe wireless power receiving device (P_(received)).

Meanwhile, although the wireless power transmitting device and thewireless power receiving device are composed of various circuitcomponents inside and constitute separate devices, since the devicesperform wireless power transmission through magnetic coupling betweenthem, they constitute one wireless power transmission system. Powertransmission characteristics uniquely determine the amount of powertransmitted by the wireless power transmitting device (transmittedpower) and the amount of power received by the wireless power receivingdevice (received power). For example, the power transmissioncharacteristics may be described by a ratio or a function of transmittedpower and received power. Therefore, knowing the power transmissioncharacteristics in advance, the wireless power transmitting device maypredict the amount of power received by the wireless power receivingdevice from the wireless power transmitted by the wireless powertransmitting device. Suppose actual received power reported by thewireless power receiving device is less than the received powerpredicted based on the power transmission characteristics; in this case,it may be considered that power loss has occurred during the powertransmission process. A power loss-based foreign object detection methodmay determine that a foreign object exists in such a case. In such acase, a power loss-based foreign object detection method may determinethat a foreign object exists. In this way, since the power loss used todetect a foreign object is also determined based on the powertransmission characteristics, it is necessary to properly understand thepower transmission characteristics to increase the reliability offoreign object detection.

The power transmission characteristics depend on the environment orinherent factors of the device that transmits wireless power. Thewireless power transmitting and receiving devices may generally usepower calibration at the start of wireless power transmission to grasppower transmission characteristics in any given wireless chargingenvironment. When power transmission characteristics are identified orconfigured by power calibration, foreign object detection may beperformed accordingly.

The power transmission characteristics may also depend on the change ofa load or change of strength of magnetic coupling. For example, when thewireless power receiving device employs multiple load steps or a varyingload (or an increasing load) or when the strength of magnetic couplingchanges due to change of positions of the wireless power transmittingand receiving devices, at least part of the power transmissioncharacteristics may change. When at least part of the power transmissioncharacteristics changes, at least part of the power calibrationparameters configured according to the previous power transmissioncharacteristics become invalid. Also, power loss and foreign objectdetection according to at least part of the configured power calibrationparameters are no longer valid. Therefore, additional power calibrationsuitable for the changed power transmission characteristics is needed.

At the time of foreign object detection due to power loss, the accuracyof a received power value transmitted periodically by the wireless powerreceiving device through a received power packet is essential; the WPCQi specification requires accuracy as high as shown in Table 3.

TABLE 3 Estimated Received Power ΔP_(r) Unit P_(r(est)) ≤ 5 W 350 mW 5 W< P_(r(est)) ≤ 10 W 500 mW 10 W < P_(r(est)) 750 mW

Referring to Table 3, when the wireless power receiving device receiveswireless power of more than 5 W, the resolution of a received powervalue required for the wireless power receiving device is larger than500 mW. Therefore, there arises a problem that a foreign objectconsuming power less than 500 mW may not be detected with the resolutionmentioned above.

To compensate for the accuracy of a received power value duringtransmission and reception of wireless power of more than 5 W, atwo-point power calibration method is used.

FIG. 10 is a state diagram illustrating a two-point power calibrationmethod, and FIG. 11 is a graph illustrating a power calibration curveaccording to the two-point power calibration method.

Referring to FIG. 10 , after completing the negotiation phase, awireless power receiving device transmits a first received power packet(RP/1) and a second received power packet (RP/2) at the start of thepower transmission step to let a wireless power transmitting deviceconstruct a two-point power calibration curve.

More specifically, the wireless power receiving device transmits thefirst received power packet (RP/1) including information about a firstcalibration data point to the wireless power transmitting device SR1.

The first received power packet (RP/1) includes a mode field and anestimated received power value field (see FIG. 13 ). The wireless powertransmitting device may confirm, through the value of the mode field ofthe first received power packet (RP/1), that a received power packet(RP) received from the wireless power receiving device is the firstreceived power packet (RP/1) including the information about the firstcalibration data point and confirm the first calibration data pointthrough the value of the estimated received power value field of thefirst received power packet (RP/1).

The first calibration data point is the start point of the powercalibration curve and may be a power level corresponding to about 10% ofa reference power level of a power transfer contract established at thenegotiation phase and may be a received power value received by thewireless power receiving device under a light load condition. The lightload condition may indicate a situation in which a load (for example,battery) is not connected electrically to the wireless power receivingdevice.

Meanwhile, the wireless power receiving device transmits a Control Error(CE) packet to the wireless power transmitting device, where the CEpacket includes a control error value. The control error value includesinformation about a deviation between a target operating point and anactual operating point of the wireless power receiving device. Forexample, when the CE value is positive, it indicates that the actualoperating point is lower than the target operating point, and thewireless power transmitting device receiving the CE value increases thepower of wireless power transmitted. On the other hand, if the CE valueis negative, it indicates that the actual operating point is higher thanthe target operating point, and the wireless power transmitting devicereceiving the CE value lowers the power of wireless power transmitted.

The wireless power transmitting device determines, based on a controlerror value included in the CE packet, whether the wireless powerreceiving device has reached a desired target operating point andresponds with ACK or NAK in response to the first received power packet(RP/1) ST1. More specifically, the wireless power transmitting devicedetermines, based on a control error value, whether the power level isstable at the first calibration data point. For example, when thecontrol error value is less than 3, the wireless power transmittingdevice may determine that the power level is stable and the wirelesspower receiving device has reached the desired target operating point;and respond with ACK in response to the first received power packet(RP/1). When the control error value is larger than 3, the wirelesspower transmitting device may determine that the power level is unstableand the wireless power receiving device has not yet reached the desiredtarget operating point; and respond with NAK in response to the firstreceived power packet (RP/1).

The wireless power receiving device continues to transmit the firstreceived power packet (RP/1) until it receives ACK from the wirelesspower transmitting device SR1. Also, to stabilize the power level at thefirst calibration data point, the wireless power receiving device alsotransmits a control error packet repeatedly to the wireless powertransmitting device.

After the power level is stabilized at the first calibration data pointand ACK is received in response to the first received power packet(RP/1) from the wireless power transmitting device, the wireless powerreceiving device transmits a second received power packet (RP/2)including information about a second calibration data point to thewireless power transmitting device SR2.

The second received power packet (RP/2) also includes a mode field andan estimated received power value field (see FIG. 13 ). The wirelesspower transmitting device may confirm, through the value of the modefield of the second received power packet (RP/2), that a received powerpacket (RP) received from the wireless power receiving device is thesecond received power packet (RP/2) including the information about thesecond calibration data point and confirm the second calibration datapoint through the value of the estimated received power value field ofthe second received power packet (RP/2).

The second calibration data point may be used to construct a powercalibration curve, correspond to a power level close to a referencepower level of a power transfer contract established in the negotiationphase, and indicate a received power value received by the wirelesspower receiving device under a connected load condition. The connectedload condition may indicate a situation in which a load is connected tothe wireless power receiving device.

The wireless power transmitting device determines, based on a controlerror value included in the CE packet, whether the wireless powerreceiving device has reached a desired target operating point andresponds with ACK or NAK in response to the second received power packet(RP/2) ST2. More specifically, the wireless power transmitting devicedetermines, based on a control error value, whether the power level isstable at the second calibration data point. For example, when thecontrol error value is less than 3, the wireless power transmittingdevice may determine that the power level is stable and the wirelesspower receiving device has reached the desired target operating point;and respond with ACK in response to the second received power packet(RP/2). When the control error value is larger than 3, the wirelesspower transmitting device may determine that the power level is unstableand the wireless power receiving device has not yet reached the desiredtarget operating point; and respond with NAK in response to the secondreceived power packet (RP/2).

The wireless power receiving device continues to transmit the secondreceived power packet (RP/2) until it receives ACK from the wirelesspower transmitting device SR2. Also, to stabilize the power level at thesecond calibration data point, the wireless power receiving device alsotransmits a control error packet repeatedly to the wireless powertransmitting device.

After the power level is stabilized at the second calibration data pointand ACK is received in response to the second received power packet(RP/2) from the wireless power transmitting device SR3, the wirelesspower receiving device and the wireless power transmitting device entera normal power transmission mode. The wireless power transmitting devicemay construct a power calibration curve based on the first receivedpower packet (RP/1) and the second received power packet (RP/2) inresponse to which ACK is transmitted and check occurrence of power lossdue to a foreign object during power transmission based on the powercalibration curve.

More specifically, the wireless power transmitting device may receive areceived power packet (for example, RP/0) from the wireless powerreceiving device during power transmission, confirm the received powervalue received by the wireless power receiving device through thereceived power packet, and assume occurrence of a power loss due to aforeign object if a difference between received power values confirmedthrough the ratio of a received power value to a received power packetcalculated by applying a transmitted power value to the powercalibration curve.

In what follows, with reference to FIG. 11 , a power calibration curveaccording to the two-point power calibration method will be described.

A wireless power transmitting device constructs a power calibrationcurve based on the first received power packet (RP/1) and the secondreceived power packet (RP/2) in response to which ACK is transmitted.

Suppose a prediction value of transmitted power is denoted byP_(t(est)), a prediction value of received power is denoted byP_(r(est)), an actual transmitted power value is denoted by P_(t), andan actual received power value is denoted by P_(r); if it is confirmedthat there exists no foreign object between the wireless powertransmitting device and the wireless power receiving device throughForeign Object Detection (FOD) before power transmission (pre-powerFOD), Eq. 1 below is satisfied.Pt(est)+δPt=Pt=Pr=Pr(est)−δPr  [Eq. 1]

In Eq. 1, δP_(t) is a prediction error value of transmitted power andmay include a power loss inherent to the wireless power transmittingdevice. δP_(r) is a prediction error value of received power and mayinclude a power loss inherent to the wireless power receiving device.

Based on Eq. 1, a calibrated power value P_((cal)) may be calculated byEq. 2 below.P(cal)=δPt+δPr=Pr(est)−Pt(est)  [Eq. 2]

Therefore, if RP/1 (the first calibration data point) and RP/2 (thesecond calibration data point) are inserted to Eq. 2, calibrated powervalues may be expressed respectively by using Eq. 3.P1(cal)=RP/1−Pt1(est)P2(cal)=RP/2−Pt2(est)  [Eq. 3]

In other words, if it is confirmed from pre-power FOD that no foreignobject is present, a relationship described by Eqs. 1 to 3 isestablished, and a calibration curve based on Eqs. 1 to 3 may beconstructed as shown in FIG. 11 .

A calibration protocol using the two points (RP/1 and RP/2) is incapableof supporting the case where the wireless power receiving device reachesfinal load power through multiple steps. Therefore, a multi-point basedpower calibration method is needed.

According to the WPC Qi ver 1.2.4, only one transmission of calibrationinformation (RP/1 and RP/2) is allowed before power transmission isstarted; thus, when the wireless power receiving device changes anoperating point (for example, a target rectified voltage) during powertransmission, the wireless power transmitting device is unable togenerate a new calibration curve during power transmission.

According to the WPC Qi ver 1.2.4, when re-calibration of power isneeded, the wireless power receiving device has to reset the wirelesspower transmitting device by transmitting an EPT/rep packet and restartthe protocol for wireless power transmission from the beginning.Therefore, a problem occurs that the wireless power receiving device hasto stop receiving power for re-calibration of power. Therefore, amulti-point based power recalibration method is required during powertransmission.

Also, RP/2 power level (the second calibration data point) may belimited depending on the battery charge state when the wireless powerreceiving device transmits the second received power packet (RP/2). Inparticular, when the battery is almost fully charged, a differencebetween RP/1 (the first calibration data point) and RP/2 (the secondcalibration data point) becomes small, which makes the power calibrationrange limited. In addition, when high power transmission is required asthe amount of battery charge is decreased due to the operation ofvarious application programs during power transmission, since thecalibration power itself lies outside the range of the initialcalibration curve, there is a problem that the calibration curve has tobe extrapolated. Therefore, to prevent extrapolation, there is a needfor a method capable of transmitting additional calibration points tothe wireless power transmitting device to extend the existingcalibration curve while maintaining an operating point (for example, atarget rectified voltage) during charging. In other words, a multi-pointcalibration method is required to extend the calibration curve usingmultiple points.

In what follows, a multi-point power calibration method that extends apower calibration curve will be described.

FIG. 12 is a flow diagram illustrating a multi-point power calibrationmethod according to one embodiment, FIG. 13 illustrates a format of areceived power packet according to one embodiment, FIG. 14 is a statediagram illustrating a multi-point power calibration method using aplurality of RP/2s according to one embodiment, FIG. 15 is a graphillustrating a power calibration curve according to a multi-point powercalibration method using a plurality of RP/2s according to oneembodiment, and FIG. 16 is a graph illustrating a power calibrationcurve according to a multi-point power calibration method using aplurality of RP/2s according to another embodiment.

Referring to FIG. 12 , according to a multi-point power calibrationprotocol that extends a power calibration curve, a wireless powerreceiving device transmits a CE packet to a wireless power transmittingdevice S1101. Since the CE packet has been already described above,specific descriptions thereof will be omitted.

Referring to FIGS. 12 and 14 , the wireless power receiving devicetransmits a first received power packet (RP/1) including informationabout a first calibration data point to the wireless power transmittingdevice S1102, SR1. The CE packet and the first received power packet(RP/1) are transmitted after the negotiation phase, which may betransmitted at the start of the power transfer phase or before the powertransfer phase.

Referring to FIG. 13 , the first received power packet (RP/1) includes amode field and an estimated received power value field. The wirelesspower transmitting device may confirm, through the value of the modefield of the first received power packet (RP/1), that a received powerpacket (RP) received from the wireless power receiving device is thefirst received power packet (RP/1) including the information about thefirst calibration data point and confirm the first calibration datapoint through the value of the estimated received power value field ofthe first received power packet (RP/1).

The first calibration data point is the start point of the powercalibration curve and may be a power level corresponding to about 10% ofa reference power level of a power transfer contract established at thenegotiation phase and may be a received power value received by thewireless power receiving device under a light load condition. The lightload condition may indicate a situation in which a load (for example,battery) is not connected electrically to the wireless power receivingdevice.

The wireless power transmitting device determines, based on a controlerror value included in the CE packet, whether the wireless powerreceiving device has reached a desired target operating point andresponds with ACK or NAK in response to the first received power packet(RP/1) ST1. More specifically, when the control error value is less thanor equal to a predetermined level, the wireless power transmittingdevice determines that the power level is stable and the wireless powerreceiving device has reached a desired target operating point; andresponds with ACK in response to the first received power packet (RP/1)S1103. When the control error value is larger than or equal to apredetermined level, the wireless power transmitting device determinesthat the power level is unstable and the wireless power receiving devicehas not yet reached a desired target operating point; and may respondwith NAK in response to the first received power packet (RP/1).

The wireless power receiving device continues to transmit the firstreceived power packet (RP/1) until it receives ACK from the wirelesspower transmitting device S1102. Also, to stabilize the power level atthe first calibration data point, the wireless power receiving devicealso transmits a control error packet repeatedly to the wireless powertransmitting device S1101.

After receiving ACK from the wireless power transmitting device inresponse to the first received power packet (RP/1), the wireless powerreceiving device transmits a second received power packet (RP/2)including information about the second calibration data point to thewireless power transmitting device S1105, SR2.

Referring to FIG. 13 , the second received power packet (RP/2) alsoincludes a mode field and an estimated received power value field (seeFIG. 13 ). The wireless power transmitting device may confirm, throughthe value of the mode field of the second received power packet (RP/2),that a received power packet (RP) received from the wireless powerreceiving device is the second received power packet (RP/2) includingthe information about the second calibration data point and confirm thesecond calibration data point through the value of the estimatedreceived power value field of the second received power packet (RP/2).In order for the wireless power transmitting device to distinguish thefirst calibration data point from the second calibration data point, themode field of the first received power packet (RP/1) and the mode fieldof the second received power packet (RP/2) have different values. Forexample, the mode field of the first received power packet (RP/1) mayhave a value of 1 (‘001’b), and the mode field of the second receivedpower packet (RP/2) may have a value of 2 (‘010’b).

The second calibration data point may be used to construct a powercalibration curve, correspond to a power level close to a referencepower level of a power transfer contract established in the negotiationphase, and indicate a received power value received by the wirelesspower receiving device under a connected load condition. The connectedload condition may indicate a situation in which a load is connected tothe wireless power receiving device.

Meanwhile, the wireless power receiving device transmits a CE packet tothe wireless power transmitting device S1104. The wireless powertransmitting device determines, based on a control error value includedin the CE packet, whether the wireless power receiving device hasreached a desired target operating point and responds with ACK or NAK inresponse to the second received power packet (RP/2) ST2. When thecontrol error value is less than or equal to a predetermined level, thewireless power transmitting device determines that the power level isstable and the wireless power receiving device has reached a desiredtarget operating point; and responds with ACK in response to the secondreceived power packet (RP/2) S1106. When the control error value islarger than or equal to a predetermined level, the wireless powertransmitting device determines that the power level is unstable and thewireless power receiving device has not yet reached a desired targetoperating point; and may respond with NAK in response to the secondreceived power packet (RP/2).

The wireless power receiving device continues to transmit the secondreceived power packet (RP/2) until it receives ACK from the wirelesspower transmitting device S1105. Also, to stabilize the power level atthe second calibration data point, the wireless power receiving devicealso transmits a control error packet repeatedly to the wireless powertransmitting device S1104.

After receiving ACK in response to the second received power packet(RP/2), the wireless power receiving device may determine whether it isnecessary to transmit consecutive calibration data points. For example,the wireless power receiving device may check whether a desired targetload power has been reached or whether new calibration data pointsoutside the range between the first calibration data point and thesecond calibration data point are required while an operating point (forexample, V_(rec) (a rectified voltage)) is maintained. In other words,when the target load power is not reached yet, the wireless powerreceiving device may check whether step-by-step increments to the targetload power are required and whether new calibration data points outsidethe range between the first calibration data point and the secondcalibration data point are required considering the change of a useenvironment of a battery being charged.

When transmission of consecutive calibration points is not required, thewireless power receiving device may transmit a received power packet(RP/0 or RP/4), of which the mode field has a value different from thoseof the first received power packet (RP/1) and the second received powerpacket (RP/2), so that the power calibration protocol may be terminatedand normal power transmission may resume SR3. The wireless powerreceiving device may transmit RP/0 or RP/4 to avoid calibration time-outso that the power calibration protocol may be terminated. Referring toFIG. 13 , RP/0 or RP/4 may also have the same format as those of thefirst received power packet (RP/1) and the second received power packet(RP/2) and includes an estimated received power value indicating anormal value. Since RP/0 or RP/4 has a mode field whose value isdifferent from those of the first received power packet (RP/1) and thesecond received power packet (RP/2), the wireless power transmittingdevice may distinguish RP/0 or RP/4 from RP/1 and RP/2.

When transmission of consecutive calibration points is required, thewireless power receiving device may transmit a third calibration point,one of the consecutive calibration points, to the wireless powertransmitting device using the second received power packet (RP/2) again.In other words, the wireless power receiving device transmits a newsecond received power packet (RP/2) including information about thethird calibration point to the wireless power transmitting device S1108,SR3.

The third calibration data point is used to construct a powercalibration curve and may be a power value higher than the secondcalibration data point to which the wireless power transmitting devicehas responded with ACK or a power value lower than the first calibrationdata point to which the wireless power transmitting device has respondedwith ACK.

Meanwhile, the wireless power receiving device transmits a CE packet tothe wireless power transmitting device S1107. The wireless powertransmitting device determines, based on a control error value includedin the CE packet, whether the wireless power receiving device hasreached a desired target operating point and responds with ACK or NAK inresponse to the new second received power packet (RP/2) ST2. When thecontrol error value is less than or equal to a predetermined level, thewireless power transmitting device determines that the power level isstable and the wireless power receiving device has reached a desiredtarget operating point; and responds with ACK in response to the newsecond received power packet (RP/2) S1109. When the control error valueis larger than or equal to a predetermined level, the wireless powertransmitting device determines that the power level is unstable and thewireless power receiving device has not yet reached a desired targetoperating point; and may respond with NAK in response to the new secondreceived power packet (RP/2).

The wireless power receiving device continues to transmit the new secondreceived power packet (RP/2) until it receives ACK from the wirelesspower transmitting device S1108. Also, to stabilize the power level atthe third calibration data point, the wireless power receiving devicealso transmits a control error packet repeatedly to the wireless powertransmitting device S1107.

Referring to FIG. 15 , the wireless power transmitting device constructsa power calibration curve based on calibration data points includedrespectively in the first received power packet (RP/1), the secondreceived power packet (RP/2), and the new second received power packet(RP/2) in response to which ACK is transmitted.

When the power calibration curve is constructed based on threecalibration data points, a first power calibration curve A1 connectingthe first calibration data point (Pt1, RP/1) and the second calibrationdata point (Pt2, RP/2) and a second power calibration curve A2connecting the second calibration data point (Pt2, RP/2) and the thirdcalibration data point (Pt3, RP/2) may be constructed.

The first power calibration curve A1 and the second power calibrationcurve A2 may be defined as first-order functions having different slopesand y-intercepts, and the wireless power transmitting device performsforeign object detection due to a loss of transmitted power using areceived power value confirmed by using a received power packet receivedfrom the wireless power receiving device, a transmitted power value, anda power calibration curve including the first power calibration curve A1and the second power calibration curve A2, S1110.

Meanwhile, depending on the needs, the wireless power receiving devicemay make the wireless power transmitting device extend the powercalibration curve by transmitting a fourth calibration data point to thewireless power transmitting device. In this case, the wireless powerreceiving device may transmit the fourth calibration point, one of theconsecutive calibration points, to the wireless power transmittingdevice by again using the second received power packet (RP/2).

The wireless power receiving device transmits a new second receivedpower packet (RP/2) including information about the fourth calibrationpoint to the wireless power transmitting device; the wireless powertransmitting device transmits ACK or NAK based on a control error valueincluded in the control error packet. Since specific descriptions aboutthe operation above are similar to what has been given abouttransmission of the second received power packet (RP/2) includinginformation about the third calibration point, detailed descriptionsthereof will be omitted.

Referring to FIG. 16 , when a power calibration curve is constructedbased on four calibration data points included in a received powerpacket in response to which ACK is transmitted, the wireless powertransmitting device may construct a first power calibration curve A1connecting the first calibration data point (Pt1, RP/1) and the secondcalibration data point (Pt2, RP/2), a second power calibration curve A2connecting the second calibration data point (Pt2, RP/2) and the thirdcalibration data point (Pt3, RP/2), and a third power calibration curveA3 connecting the third calibration data point (Pt3, RP/2) and thefourth calibration data point (Pt4, RP/2); and perform foreign objectdetection using the constructed power calibration curves.

In a similar way, the wireless power receiving device and the wirelesspower transmitting device may construct a multi-point power calibrationcurve using one first received power packet (RP/1) and a plurality ofsecond received power packets (RP/2).

Meanwhile, a calibration time-out may be configured for the powercalibration protocol. This is intended to prevent a foreign object frombeing inserted while the power calibration protocol is proceeding.

The calibration time-out may include calibration time-out of thewireless power receiving device (PRx calibration time-out) andcalibration time-out of the wireless power transmitting device (PTxcalibration time-out).

The calibration time-out of the wireless power receiving device refersto the time during which the wireless power receiving device performspower calibration, which, for example, may be defined as the timerequired to transmit RP/0 or RP/4 after transmission of the first RP/1.For example, the calibration time-out of the wireless power receivingdevice may be configured to be 16 seconds.

The calibration time-out of the wireless power transmitting device maybe defined as the time required to transmit the first ACK in response toRP/2 after the wireless power transmitting device receives the firstRP/1. The calibration time-out of the wireless power transmitting devicemay be smaller than the calibration time-out of the wireless powerreceiving device, which, for example, may be configured to be 10seconds.

FIG. 17 is a state diagram illustrating a multi-point power calibrationmethod using RP/3 according to one embodiment, and FIG. 18 is a graphillustrating a power calibration curve according to a multi-point powercalibration method using RP/3 according to one embodiment.

Referring to FIG. 17 , S1201 to S1206 steps of the multi-point powercalibration protocol that extends a power calibration curve using RP/3are the same as the S1101 to S1106 steps of FIG. 12 . Therefore,detailed descriptions thereof will be omitted.

However, different from the embodiments described with reference toFIGS. 12 to 16 , when transmission of consecutive calibration points isneeded, a wireless power receiving device according to the presentembodiment transmits a third calibration point, one of the consecutivecalibration points, by using the third received power packet (RP/3)rather than the second received power packet (RP/2).

The third received power packet (RP/3) may have the same format as thoseof the first received power packet (RP/1) and the second received powerpacket (RP/2) (see FIG. 13 ). However, the mode field of the thirdreceived power packet (RP/3) may have a different value from the modefield values of the first received power packet (RP/1) and the secondreceived power packet (RP/2). For example, the mode field of the firstreceived power packet (RP/1) may have a value of 1 (‘001’b), the modefield of the second received power packet (RP/2) may have a value of 2(‘010’b), and the mode field of the third received packet (RP/3) mayhave a value of 3 (‘011’b).

In other words, after the S1206 step, when transmission of consecutivecalibration points is required, the wireless power receiving devicetransmits the third received power packet (RP/3) including informationabout the third calibration point to the wireless power transmittingdevice S1208.

Meanwhile, the wireless power receiving device transmits a CE packet tothe wireless power transmitting device S1207. The wireless powertransmitting device determines, based on a control error value includedin the CE packet, whether the wireless power receiving device hasreached a desired target operating point and responds with ACK or NAK inresponse to the third received power packet (RP/3). When the controlerror value is less than or equal to a predetermined level, the wirelesspower transmitting device determines that the power level is stable andthe wireless power receiving device has reached a desired targetoperating point; and responds with ACK in response to the third receivedpower packet (RP/3) S1209. When the control error value is larger thanor equal to a predetermined level, the wireless power transmittingdevice determines that the power level is unstable and the wirelesspower receiving device has not yet reached a desired target operatingpoint; and may respond with NAK in response to the third received powerpacket (RP/3).

The wireless power receiving device continues to transmit the thirdreceived power packet (RP/3) until it receives ACK from the wirelesspower transmitting device S1208. Also, to stabilize the power level atthe third calibration data point, the wireless power receiving devicealso transmits a control error packet repeatedly to the wireless powertransmitting device S1207.

Referring to FIG. 18 , the wireless power transmitting device constructsa power calibration curve based on calibration data points includedrespectively in the first received power packet (RP/1), the secondreceived power packet (RP/2), and the third received power packet (RP/3)in response to which ACK is transmitted.

When the power calibration curve is constructed based on threecalibration data points, the wireless power transmitting device mayconstruct a first power calibration curve B1 connecting the firstcalibration data point (Pt1, RP/1) and the second calibration data point(Pt2, RP/2) and a second power calibration curve B2 connecting thesecond calibration data point (Pt2, RP/2) and the third calibration datapoint (Pt3, RP/3) may be constructed.

The first power calibration curve B1 and the second power calibrationcurve B2 may be defined as first-order functions having different slopesand y-intercepts, and the wireless power transmitting device performsforeign object detection due to a loss of transmitted power using areceived power value confirmed by using a received power packet receivedfrom the wireless power receiving device, a transmitted power value, anda power calibration curve including the first power calibration curve B1and the second power calibration curve B2, S1210.

As described above, since a power calibration curve may be extended, thecalibration range is increased so that a broader range of power valuesmay be calibrated, and since the calibration reliability is improved,the reliability of foreign object detection based on power loss is alsoincreased.

In what follows, a multi-point power calibration method forre-calibrating a power calibration curve will be described.

FIG. 19 is a flow diagram illustrating a power re-calibration methodaccording to one embodiment, FIG. 20 is a state diagram illustrating apower re-calibration method according to one embodiment, and FIG. 21 isa graph illustrating a power calibration curve according to a powerre-calibration method according to another embodiment.

A power re-calibration protocol according to one embodiment may bedistinguished by an initial calibration protocol and a follow-upcalibration protocol. Referring to FIG. 19 , the initial calibrationprotocol includes the S1301 to S1306 steps, and the follow-upcalibration protocol includes the S1310 to S1315 steps.

The S1301 to S1306 steps of the initial calibration protocol are thesame as the S1101 to S1106 steps of FIG. 12 . Therefore, detaileddescriptions thereof will be omitted.

Although the initial calibration protocol shown in FIG. 19 uses thetwo-point calibration protocol constructing a power calibration curvebased on two calibration data points, the initial calibration protocolmay use the multi-point calibration protocol constructing a powercalibration curve based on three or more calibration data pointsdescribed with reference to FIGS. 12 to 18 .

Suppose RP/0 or RP/4 is transmitted to terminate the initial calibrationprotocol since transmission of consecutive calibration points is nolonger needed after ACK is received in response to the second receivedpower packet (RP/2) including information about the second calibrationdata point transmitted by the wireless power receiving device; in thiscase, the initial calibration protocol proceeds using the two-pointcalibration protocol.

Meanwhile, when transmission of consecutive calibration points is neededafter ACK is received in response to the second received power packet(RP/2) including information about the second calibration data pointtransmitted by the wireless power receiving device and the second orthird received power packet including information about the thirdcalibration data point is transmitted, the initial calibration protocolproceeds based on the multi-point calibration protocol.

If the initial calibration protocol is completed, the wireless powertransmitting device constructs a power calibration curve according tothe initial calibration protocol and performs foreign object detectionbased on the power calibration curve S1307.

When it is determined from the result of foreign object detection that aforeign object does not exist, the power transfer phase is carried out,and the wireless power transmitting device transmits wireless power tothe wireless power receiving device S1308. For the convenience ofdescription, FIG. 19 illustrates a situation where the power transferphase is carried out after the S1307 step; however, the initialcalibration protocol may be carried out from the start of the powertransfer phase.

When the wireless power receiving device changes a target operatingpoint (for example, a target rectified voltage) in the middle ofwireless power transfer S1309, a follow-up calibration protocol iscarried out, and the wireless power receiving device transmits a newfirst received power packet (RP/1) including information about a newfirst calibration data point to the wireless power transmitting device(S1311, SR4→SR1). Referring to FIG. 21 , for example, the wireless powerreceiving device may change the target operating point from a firstoperating point (5V) to a second operating point (12V).

The new first received power packet (RP/1) also has the same format asother received power packets. The new first received power packet (RP/1)has the same mode field value as the first received power packet (RP/1)transmitted in the S1302 step. However, since the new first receivedpower packet (RP/1) includes information about calibration data pointsdifferent from the information included in the first received powerpacket (RP/1) transmitted in the S1302 step, the value of the estimatedreceived power value field may be different from that of the firstreceived power packet (RP/1) transmitted in the S1302 step.

The wireless power transmitting device may confirm, through the value ofthe mode field of the new first received power packet (RP/1), that thereceived power packet (RP) received from the wireless power receivingdevice is a new first received power packet (RP/1) including informationabout a new first calibration data point and may confirm the new firstcalibration data point through the value of the estimated received powervalue field of the new first received power packet (RP/1). The new firstcalibration data point becomes a start point of a power calibrationcurve updated through the re-calibration protocol.

Meanwhile, the wireless power receiving device transmits a CE packet tothe wireless power transmitting device S1310. The wireless powertransmitting device determines, based on a control error value includedin the CE packet, whether the wireless power receiving device hasreached a desired target operating point and responds with ACK or NAK inresponse to the new second received power packet (RP/2) ST2. Sincedetailed descriptions related to the above have already been given, theywill be omitted.

The wireless power receiving device continues to transmit the new firstreceived power packet (RP/1) and the control error packet S1310, S1311until it receives ACK from the wireless power transmitting device S1312.

After receiving ACK from the wireless power transmitting device inresponse to the new first received power packet (RP/1), the wirelesspower receiving device transmits the new second received power packet(RP/2) including information about the new second calibration data pointto the wireless power transmitting device S1314, SR2.

The new second received power packet (RP/2) also has the same format asother received power packets. The new second received power packet(RP/2) has the same mode field value as the second received power packet(RP/2) transmitted in the S1305 step. However, since the new secondreceived power packet (RP/2) includes information about calibration datapoints different from the information included in the second receivedpower packet (RP/2) transmitted in the S1305 step, the value of theestimated received power value field may be different from that of thesecond received power packet (RP/2) transmitted in the S1305 step.

The wireless power transmitting device may confirm, through the value ofthe mode field of the new second received power packet (RP/2), that thereceived power packet (RP) received from the wireless power receivingdevice is a new second received power packet (RP/2) includinginformation about a new second calibration data point and may confirmthe new second calibration data point through the value of the estimatedreceived power value field of the new second received power packet(RP/2). The new second calibration data point constitutes a point forconstructing a power calibration curve updated through there-calibration protocol.

Meanwhile, the wireless power receiving device transmits a CE packet tothe wireless power transmitting device S1313. The wireless powertransmitting device determines, based on a control error value includedin the CE packet, whether the wireless power receiving device hasreached a desired target operating point and responds with ACK or NAK inresponse to the new second received power packet (RP/2) ST2. Sincedetailed descriptions related to the above have already been given, theywill be omitted.

The wireless power receiving device continues to transmit the new secondreceived power packet (RP/2) and the control error packet S1313, S1314until it receives ACK from the wireless power transmitting device S1315.

After receiving ACK in response to the new second received power packet(RP/2), the wireless power receiving device may determine whether it isnecessary to transmit consecutive calibration data points.

When transmission of consecutive calibration points is not required, thewireless power receiving device may transmit a received power packet(RP/0 or RP/4), of which the mode field has a value different from thoseof the first received power packet (RP/1) and the second received powerpacket (RP/2), so that the power calibration protocol may be terminatedand normal power transmission may resume SR3.

The wireless power transmitting device updates the power calibrationcurve based on the new first and second calibration points receivedthrough the follow-up calibration protocol and performs foreign objectdetection using the updated power calibration curve S1316.

Although FIG. 19 illustrates an example in which the follow-upcalibration protocol also proceeds based on the two-point calibrationprotocol for the convenience of descriptions, when the wireless powerreceiving device transmits the second or third received power packetincluding information about the third calibration data point accordinglyas transmission of consecutive calibration points is needed after theS1315 step, the follow-up calibration protocol proceeds based on themulti-point calibration protocol. In this case, the wireless powertransmitting device performs foreign object detection using a powercalibration curve updated according to the multi-point calibrationprotocol S1316.

Referring to FIG. 21 , an initial calibration curve is constructedaccordingly as the initial calibration protocol proceeds at the firstoperating point (5V) based on the multi-point calibration protocol usingone RP/1 and a plurality of RP/2s described with reference to FIG. 12 .Afterwards, the operating point is changed to the second operating point(12V), and the power calibration curve is updated accordingly as thefollow-up calibration protocol also proceeds at the second operatingpoint based on the multi-point calibration protocol using one RP/1 and aplurality of RP/2s.

According to the power re-calibration method, when the wireless powerreceiving device changes an operating point (for example, a targetrectified voltage) during power transmission, power re-calibration maybe performed without resetting the wireless power transmitting device.

Therefore, by resetting the wireless power transmitting device, chargingtime for the wireless power receiving device may be prevented from beingelongated, and since an update of the power calibration curve due to thechange of the operating point is made possible, reliability of foreignobject detection is also increased.

In the above, a multi-point power calibration method extending a powercalibration curve and a multi-point power calibration methodre-calibrating the power calibration curve have been described. In whatfollows, a power calibration method combining the multi-point powercalibration method extending a power calibration curve and themulti-point power calibration method re-calibrating the powercalibration curve will be described.

FIG. 22 is a flow diagram illustrating a power calibration methodaccording to one embodiment.

Referring to FIG. 22 , the wireless power transmitting device and thewireless power receiving device go through the ping phase S1401, theconfiguration phase S1402, and the negotiation phase S1403; and proceedwith a calibration protocol. The wireless power receiving devicetransmits a first calibration data point and a second calibration datapoint to the wireless power transmitting device by transmitting thefirst received power packet (RP/1) and the second received power packet(RP/2) S1404.

The wireless power transmitting device constructs a calibration curveusing the first calibration data point and the second calibration datapoint of the first received power packet (RP/1) and the second receivedpower packet (RP/2) in response to which ACK is transmitted; transmitswireless power based on the calibration curve S1405; and performsforeign object detection.

Afterwards, as the wireless power receiving device changes a targetoperating point (for example, a target rectified voltage), a multi-pointpower calibration method extending the power calibration curve or amulti-point power calibration method re-calibrating (or updating) thepower calibration curve is used for further progress.

When the wireless power receiving device does not change the targetoperating point S1406 and it is necessary to transmit consecutivecalibration points, a multi-point power calibration method extending thepower calibration curve is used for further progress S1407. As describedabove, the multi-point power calibration method extending the powercalibration curve transmits the third calibration data point to thewireless power transmitting device using a new second received powerpacket (RP/2) or a third received power packet (RP/3). The wirelesspower transmitting device constructs a power calibration curve using thefirst and second calibration data points received in the S1404 step andthe third calibration data point received in the S1407 step.

Meanwhile, when the wireless power receiving device changes the targetoperating point S1406, the multi-point power calibration methodre-calibrating (or updating) the power calibration curve is used. Asdescribed above, the multi-point power calibration method re-calibrating(or updating) the power calibration curve transmits new first and secondcalibration data points to the wireless power transmitting device usingthe new first received power packet (RP/1) and the new second receivedpower packet (RP/2). The wireless power transmitting devicere-calibrates (or updates) the power calibration curve using newlyreceived first and second calibration data points.

In other words, the wireless power receiving device and the wirelesspower transmitting device proceed with a calibration protocol extendingan existing power calibration curve or a calibration protocol updatingthe existing power calibration curve depending on whether the targetoperating point is changed.

The wireless power transmitting device according to the embodiments ofFIGS. 10 to 22 corresponds to the wireless power transmitting device orthe wireless power transmitter or the power transmitting unit disclosedin FIGS. 1 to 9 . Therefore, the operation of the wireless powertransmitting device according to the present embodiment is implementedby a combination of one or two or more of the constituting elements ofthe wireless power transmitting device of FIGS. 1 to 9 . For example,the communication/control unit 120 may perform reception of data packetsfor foreign object detection by the wireless power transmitting device,construction of a power calibration curve, extension and/or update,execution of a foreign object detection method, transmission of ACK/NAKdue to the result of the foreign object detection, and so on.

Also, the wireless power receiving device according to the embodimentsof FIGS. 10 to 22 corresponds to the wireless power receiving device orthe wireless power receiver or the power receiving unit disclosed inFIGS. 1 to 9 . Therefore, the operation of the wireless power receivingdevice according to the present embodiment is implemented by acombination of one or two or more of the constituting elements of thewireless power receiving device of FIGS. 1 to 9 . For example, thecommunication/control unit 220 may perform transmission of data packetsfor foreign object detection by the wireless power receiving device,reception of ACK/NAK due to the result of the foreign object detection,and so on.

Since the wireless power transmitting method and apparatus or thewireless power receiver and method according to an embodiment of thepresent disclosure do not necessarily include all the elements oroperations, the wireless power transmitter and method and the wirelesspower transmitter and method may be performed with the above-mentionedcomponents or some or all of the operations. Also, embodiments of theabove-described wireless power transmitter and method, or receivingapparatus and method may be performed in combination with each other.Also, each element or operation described above is necessarily performedin the order as described, and an operation described later may beperformed prior to an operation described earlier.

The description above is merely illustrating the technical spirit of thepresent disclosure, and various changes and modifications may be made bythose skilled in the art without departing from the essentialcharacteristics of the present disclosure. Therefore, the embodiments ofthe present disclosure described above may be implemented separately orin combination with each other.

Therefore, the embodiments disclosed in the present disclosure areintended to illustrate rather than limit the scope of the presentdisclosure, and the scope of the technical spirit of the presentdisclosure is not limited by these embodiments. The scope of the presentdisclosure should be construed by claims below, and all technicalspirits within a range equivalent to claims should be construed as beingincluded in the right scope of the present disclosure.

What is claimed is:
 1. In a wireless power transmitter transmittingwireless power to a wireless power receiver, the wireless powertransmitter configured to: receive a first received power packetincluding a first estimated received power value for a first calibrationdata point from the wireless power receiver; transmit ACK in response tothe first received power packet; receive a second received power packetincluding a second estimated received power value for a secondcalibration data point from the wireless power receiver; transmit ACK inresponse to the second received power packet; receive a new secondreceived power packet including a third estimated received power valuefor a third calibration data point from the wireless power receiver;transmit ACK in response to the new second received power packet; andconstruct a power calibration curve based on the first estimatedreceived power value, the second estimated received power value, and thethird estimated received power value.
 2. The wireless power transmitterof claim 1, further configured to receive a control error packetincluding a control error value from the wireless power receiver andtransmit ACK in response to the first received power packet, the secondreceived power packet, and the new second received power packet based onthe control error value.
 3. The wireless power transmitter of claim 1,further configured to calculate a power loss value of the wireless powertransmitted to the wireless power receiver based on the powercalibration curve and detect a foreign object existing between thewireless power transmitter and the wireless power receiver using thepower loss value.
 4. The wireless power transmitter of claim 1, whereinthe first received power packet, the second received power packet, andthe new second received power packet have the same packet structureincluding a mode field; and the mode field of the first received powerpacket has a value different from those of the mode fields of the secondreceived power packet and the new second received power packet.
 5. Thewireless power transmitter of claim 4, wherein mode fields of the secondreceived power packet and the new second received power packet have thesame value.
 6. In a wireless power receiver receiving wireless powerfrom a wireless power transmitter, the wireless power receiverconfigured to: transmit a first received power packet including a firstestimated received power value for a first calibration data point to thewireless power transmitter; receive ACK in response to the firstreceived power packet from the wireless power transmitter; transmit asecond received power packet including a second estimated received powervalue for a second calibration data point to the wireless powertransmitter; receive ACK in response to the second received power packetfrom the wireless power transmitter; transmit a new second receivedpower packet including a third estimated received power value for athird calibration data point to the wireless power transmitter; andreceive ACK in response to the new second received power packet from thewireless power transmitter.
 7. The wireless power receiver of claim 6,further configured to continue to transmit the first received powerpacket until ACK is received in response to the first received powerpacket from the wireless power transmitter.
 8. The wireless powerreceiver of claim 6, further configured to continue to transmit thesecond received power packet until ACK is received in response to thesecond received power packet from the wireless power transmitter.
 9. Thewireless power receiver of claim 6, further configured to continue totransmit the new second received power packet until ACK is received inresponse to the new second received power packet from the wireless powertransmitter.
 10. The wireless power receiver of claim 6, furtherconfigured to transmit a control error packet including a control errorvalue to the wireless power transmitter and receive, from the wirelesspower transmitter, ACK in response to the first received power packet,the second received power packet, and the new second received powerpacket based on the control error value.
 11. The wireless power receiverof claim 6, further configured to terminate a power calibration protocolby transmitting a received power packet including an estimated receivedpower value for a normal value to the wireless power transmitter. 12.The wireless power receiver of claim 6, wherein the first received powerpacket, the second received power packet, and the new second receivedpower packet have the same packet structure including a mode field; andthe mode field of the first received power packet has a value differentfrom those of the mode fields of the second received power packet andthe new second received power packet.
 13. The wireless power receiver ofclaim 6, wherein mode fields of the second received power packet and thenew second received power packet have the same value.
 14. In a wirelesspower receiver receiving wireless power from a wireless powertransmitter, the wireless power receiver configured to: transmit a firstreceived power packet including a first estimated received power valuefor a first calibration data point to the wireless power transmitter;receive ACK in response to the first received power packet from thewireless power transmitter; transmit a second received power packetincluding a second estimated received power value for a secondcalibration data point to the wireless power transmitter; receive ACK inresponse to the second received power packet from the wireless powertransmitter; and based on change of a target operating point, transmit anew second received power packet including a third estimated receivedpower value for a third calibration data point to the wireless powertransmitter or transmit a new first received power packet including anew first estimated received power value for anew first calibration datapoint and a new second received power packet including a new secondestimated received power value for a new second calibrated data point tothe wireless power transmitter.
 15. The wireless power receiver of claim14, further configured to do not changing the target operating point;transmit the new second received power packet including the thirdestimated received power value for the third calibration data point; andreceive ACK in response to the new second received power packetincluding the third estimated received power value from the wirelesspower transmitter.
 16. The wireless power receiver of claim 15, furtherconfigured to continue to transmit the new second received power packetincluding the third estimated received power value until ACK is receivedin response to the new second received power packet including the thirdestimated received power from the wireless power transmitter.
 17. Thewireless power receiver of claim 14, further configured to change thetarget operating point; transmit the new first received power packet;receive ACK in response to the new first received power packet from thewireless power transmitter; transmit the new second received powerpacket including the new second estimated received power value; andreceive ACK in response to the new second received power packetincluding the new second estimated received power value from thewireless power transmitter.
 18. The wireless power receiver of claim 17,further configured to continue to transmit the new first received powerpacket until ACK is received in response to the new first received powerpacket from the wireless power transmitter and continue to transmit thenew second received power packet including the new second estimatedreceived power value until ACK is received in response to the new secondreceived power packet including the new second estimated received powervalue from the wireless power transmitter.
 19. The wireless powerreceiver of claim 14, wherein the first received power packet, thesecond received power packet, the new first received power packet, andthe new second received power packet have the same packet structureincluding a mode field; and the mode fields of the first received powerpacket and the new first received power packet have a value differentfrom those of the mode fields of the second received power packet andthe new second received power packet.
 20. The wireless power receiver ofclaim 19, wherein mode fields of the first received power packet and thenew first received power packet have the same value, and mode fields ofthe second received power packet and the new second received powerpacket have the same value.